scythe-codegen 0.14.0

use scythe_backend::manifest::BackendManifest;
use scythe_backend::naming::{
    enum_type_name, enum_variant_name, fn_name, row_struct_name, to_camel_case, to_pascal_case,
};
use scythe_backend::types::resolve_type;
use std::fmt::Write;

use scythe_core::analyzer::{AnalyzedQuery, CompositeInfo, EnumInfo};
use scythe_core::errors::{ErrorCode, ScytheError};
use scythe_core::parser::QueryCommand;

use crate::backend_options::reject_unknown_options;
use crate::backend_trait::GroupedQueryFn;
use crate::backend_trait::{CodegenBackend, ResolvedColumn, ResolvedParam};
use crate::backends::typescript_common::{
    TsFieldCase, TsRowShape, TsRowType, escape_ts_template_literal, generate_grouped_interface_structs,
    generate_js_grouped_typedef_structs, generate_js_typedef, generate_js_typedef_row_struct, generate_jsdoc_fn_header,
    generate_ts_grouped_fold_body, generate_ts_interface_row_struct, generate_ts_many_row_remap,
    generate_ts_one_row_remap, generate_ts_union_row_struct, generate_zod_enum, generate_zod_grouped_structs,
    generate_zod_row_struct, generate_zod_union_row_struct, js_fn_signature_line, js_type_cast, parse_bool_option,
};
use crate::singularize;

const DEFAULT_MANIFEST_TOML: &str = include_str!("../../manifests/typescript-postgres.toml");
const DEFAULT_MANIFEST_REDSHIFT: &str = include_str!("../../manifests/typescript-postgres.redshift.toml");

pub struct TypescriptPostgresBackend {
    manifest: BackendManifest,
    row_type: TsRowType,
    /// Emit outer-join nullability as a discriminated union instead of
    /// independent per-column optionals. Opt-in: the flat shape stays the
    /// default and the cross-target shape.
    outer_join_unions: bool,
    /// When true, only emit type definitions (interfaces/Zod schemas, enums,
    /// composites) — no query functions, and no `postgres` driver import
    /// (which would otherwise be unused).
    structs_only: bool,
    /// Under `Camel`, `:one`/`:opt`/`:many` reconstruct the row field by
    /// field from the driver's raw (snake_case) keys instead of trusting the
    /// `sql<StructName[]>` tag's generic. `Snake` (the default) keeps that
    /// generic, which is sound there.
    field_case: TsFieldCase,
    /// Emit plain, JSDoc-annotated `.js` instead of `.ts` -- the
    /// `javascript-postgres` registry name (#81). See
    /// `TypescriptPgBackend::js_mode` for the shared rationale, including why
    /// `row_type = "zod"`, `outer_join_unions`, and `field_case =
    /// "camelCase"` are rejected outright in this mode.
    js_mode: bool,
}

impl TypescriptPostgresBackend {
    pub fn new(engine: &str) -> Result<Self, ScytheError> {
        let default_toml = match engine {
            "postgresql" | "postgres" | "pg" => DEFAULT_MANIFEST_TOML,
            "redshift" => DEFAULT_MANIFEST_REDSHIFT,
            _ => {
                return Err(ScytheError::new(
                    ErrorCode::InvalidConfig,
                    format!(
                        "typescript-postgres only supports PostgreSQL/Redshift, got engine '{}'",
                        engine
                    ),
                ));
            }
        };
        let manifest = super::parse_manifest(default_toml)?;
        Ok(Self {
            manifest,
            row_type: TsRowType::default(),
            outer_join_unions: false,
            structs_only: false,
            field_case: TsFieldCase::default(),
            js_mode: false,
        })
    }

    /// As [`Self::new`], but selecting the `javascript-postgres` JSDoc emit mode.
    pub fn new_js(engine: &str) -> Result<Self, ScytheError> {
        let mut backend = Self::new(engine)?;
        backend.js_mode = true;
        Ok(backend)
    }
}

impl CodegenBackend for TypescriptPostgresBackend {
    fn name(&self) -> &str {
        if self.js_mode {
            "javascript-postgres"
        } else {
            "typescript-postgres"
        }
    }

    /// The manifest is shared with `typescript-postgres` and says `ts`; JSDoc
    /// output is plain JavaScript and must land in a `.js` file to be runnable.
    fn output_extension(&self) -> &str {
        if self.js_mode {
            "js"
        } else {
            &self.manifest.backend.file_extension
        }
    }

    fn manifest(&self) -> &scythe_backend::manifest::BackendManifest {
        &self.manifest
    }

    fn manifest_mut(&mut self) -> &mut scythe_backend::manifest::BackendManifest {
        &mut self.manifest
    }

    fn supported_engines(&self) -> &[&str] {
        &["postgresql", "redshift"]
    }

    fn file_header(&self) -> String {
        // See `TypescriptPgBackend::file_header` for why `.js` output needs
        // no import at all: the driver type goes straight into the JSDoc
        // `@param` tag as `import("postgres").Sql`, and Zod is rejected in
        // this mode.
        if self.js_mode {
            // Nothing left for this header to carry: the "do not edit"
            // notice lives in the scythe:provenance line every backend emits.
            return String::new();
        }
        if self.structs_only {
            if self.row_type == TsRowType::Zod {
                return "import { z } from \"zod\";\n".to_string();
            }
            return String::new();
        }
        let mut header = "import type { Sql } from \"postgres\";\n".to_string();
        if self.row_type == TsRowType::Zod {
            header.push_str("import { z } from \"zod\";\n");
        }
        header
    }

    fn generate_row_struct(&self, query_name: &str, columns: &[ResolvedColumn]) -> Result<String, ScytheError> {
        let struct_name = row_struct_name(query_name, &self.manifest.naming);
        if self.js_mode {
            return Ok(generate_js_typedef_row_struct(&struct_name, query_name, columns));
        }
        if self.row_type == TsRowType::Zod {
            if self.outer_join_unions {
                return Ok(generate_zod_union_row_struct(&struct_name, query_name, columns));
            }
            return Ok(generate_zod_row_struct(&struct_name, query_name, columns));
        }
        if self.outer_join_unions {
            return Ok(generate_ts_union_row_struct(&struct_name, query_name, columns, None));
        }
        Ok(generate_ts_interface_row_struct(&struct_name, query_name, columns))
    }

    fn generate_model_struct(&self, table_name: &str, columns: &[ResolvedColumn]) -> Result<String, ScytheError> {
        let singular = singularize(table_name);
        let name = to_pascal_case(&singular);
        self.generate_row_struct(&name, columns)
    }

    fn generate_query_fn(
        &self,
        analyzed: &AnalyzedQuery,
        struct_name: &str,
        columns: &[ResolvedColumn],
        params: &[ResolvedParam],
    ) -> Result<String, ScytheError> {
        if self.js_mode {
            return self.generate_query_fn_js(analyzed, struct_name, params);
        }
        if self.structs_only {
            return Ok(String::new());
        }

        let func_name = fn_name(&analyzed.name, &self.manifest.naming);
        let mut out = String::new();

        let sql_clean = super::clean_sql_with_optional(&analyzed.sql, &analyzed.optional_params, &analyzed.params);
        // Escape the user's SQL before postgres.js's own `${}` interpolations
        // are inserted below — otherwise a literal `${` in the user's SQL
        // becomes a live binding, and escaping afterwards would also mangle
        // the interpolations this pass is about to add.
        let sql_clean = escape_ts_template_literal(&sql_clean);
        let name_map: std::collections::HashMap<u32, String> = analyzed
            .params
            .iter()
            .zip(params.iter())
            .map(|(ap, rp)| (ap.position as u32, rp.field_name.clone()))
            .collect();
        let sql_template = super::rewrite_pg_placeholders(&sql_clean, |n| {
            format!("${{{}}}", name_map.get(&n).map_or("?", |s| s.as_str()))
        });

        let write_fn_sig = |out: &mut String, name: &str, sig_params: &[(String, String)], ret: &str| {
            let params_inline = sig_params
                .iter()
                .map(|(n, t)| format!("{n}: {t}"))
                .collect::<Vec<_>>()
                .join(", ");
            let oneliner = format!("export async function {}({}): {} {{", name, params_inline, ret);
            if oneliner.len() <= 80 {
                let _ = writeln!(out, "{}", oneliner);
            } else {
                let _ = writeln!(out, "export async function {}(", name);
                for (n, t) in sig_params {
                    let _ = writeln!(out, "\t{}: {},", n, t);
                }
                let _ = writeln!(out, "): {} {{", ret);
            }
        };

        let query_sig_params: Vec<(String, String)> = std::iter::once(("sql".to_string(), "Sql".to_string()))
            .chain(params.iter().map(|p| (p.field_name.clone(), p.full_type.clone())))
            .collect();

        match &analyzed.command {
            QueryCommand::One | QueryCommand::Opt => {
                let _ = writeln!(out, "/** Fetch a single {} or null. */", struct_name);
                let ret = format!("Promise<{} | null>", struct_name);
                write_fn_sig(&mut out, &func_name, &query_sig_params, &ret);
                match self.field_case {
                    TsFieldCase::Snake => {
                        let _ = writeln!(out, "\tconst rows = await sql<{}[]>`", struct_name);
                        let _ = writeln!(out, "    {}", sql_template);
                        let _ = writeln!(out, "  `;");
                        let _ = writeln!(out, "\treturn rows[0] ?? null;");
                    }
                    TsFieldCase::Camel => {
                        let _ = writeln!(out, "\tconst rows = await sql<Record<string, unknown>[]>`");
                        let _ = writeln!(out, "    {}", sql_template);
                        let _ = writeln!(out, "  `;");
                        let _ = writeln!(out, "\tconst row = rows[0];");
                        out.push_str(&generate_ts_one_row_remap(
                            columns,
                            TsRowShape::from_outer_join_unions(self.outer_join_unions),
                            |name, ty| format!("row['{name}'] as {ty}"),
                        ));
                    }
                }
                let _ = write!(out, "}}");
            }
            QueryCommand::Batch => {
                let batch_fn_name = format!("{}Batch", func_name);
                if params.len() > 1 {
                    let params_type_name = format!("{}BatchParams", struct_name);
                    let _ = writeln!(out, "/** Params for {} batch operation. */", struct_name);
                    let _ = writeln!(out, "export interface {} {{", params_type_name);
                    for p in params {
                        let _ = writeln!(out, "\t{}: {};", p.field_name, p.full_type);
                    }
                    let _ = writeln!(out, "}}");
                    let _ = writeln!(out);
                    let _ = writeln!(
                        out,
                        "/** Execute {} for each item in the batch within a transaction. */",
                        analyzed.name
                    );
                    let batch_sig_params = vec![
                        ("sql".to_string(), "Sql".to_string()),
                        ("items".to_string(), format!("{}[]", params_type_name)),
                    ];
                    write_fn_sig(&mut out, &batch_fn_name, &batch_sig_params, "Promise<void>");
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (const item of items) {{");
                    let batch_sql = {
                        let mut s = sql_clean.clone();
                        let mut indexed: Vec<(i64, &str)> = analyzed
                            .params
                            .iter()
                            .zip(params.iter())
                            .map(|(ap, rp)| (ap.position, rp.field_name.as_str()))
                            .collect();
                        indexed.sort_by_key(|b| std::cmp::Reverse(b.0));
                        for (pos, field_name) in indexed {
                            let placeholder = format!("${}", pos);
                            let replacement = format!("${{item.{}}}", field_name);
                            s = s.replace(&placeholder, &replacement);
                        }
                        s
                    };
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", batch_sql);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                } else if params.len() == 1 {
                    let _ = writeln!(
                        out,
                        "/** Execute {} for each item in the batch within a transaction. */",
                        analyzed.name
                    );
                    let batch_sig_params = vec![
                        ("sql".to_string(), "Sql".to_string()),
                        ("items".to_string(), format!("{}[]", params[0].full_type)),
                    ];
                    write_fn_sig(&mut out, &batch_fn_name, &batch_sig_params, "Promise<void>");
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (const item of items) {{");
                    let batch_sql = sql_template.replace(&format!("${{{}}}", params[0].field_name), "${item}");
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", batch_sql);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                } else {
                    let _ = writeln!(
                        out,
                        "/** Execute {} for each item in the batch within a transaction. */",
                        analyzed.name
                    );
                    let batch_sig_params = vec![
                        ("sql".to_string(), "Sql".to_string()),
                        ("count".to_string(), "number".to_string()),
                    ];
                    write_fn_sig(&mut out, &batch_fn_name, &batch_sig_params, "Promise<void>");
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (let i = 0; i < count; i++) {{");
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", sql_template);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                }
            }
            QueryCommand::Many => {
                let _ = writeln!(out, "/** Fetch all {} rows. */", struct_name);
                let ret = format!("Promise<{}[]>", struct_name);
                write_fn_sig(&mut out, &func_name, &query_sig_params, &ret);
                match self.field_case {
                    TsFieldCase::Snake => {
                        let _ = writeln!(out, "\tconst rows = await sql<{}[]>`", struct_name);
                        let _ = writeln!(out, "    {}", sql_template);
                        let _ = writeln!(out, "  `;");
                        let _ = writeln!(out, "\treturn rows;");
                    }
                    TsFieldCase::Camel => {
                        let _ = writeln!(out, "\tconst rows = await sql<Record<string, unknown>[]>`");
                        let _ = writeln!(out, "    {}", sql_template);
                        let _ = writeln!(out, "  `;");
                        out.push_str(&generate_ts_many_row_remap(
                            columns,
                            TsRowShape::from_outer_join_unions(self.outer_join_unions),
                            |name, ty| format!("row['{name}'] as {ty}"),
                        ));
                    }
                }
                let _ = write!(out, "}}");
            }
            QueryCommand::Exec => {
                let _ = writeln!(out, "/** Execute a query returning no rows. */");
                write_fn_sig(&mut out, &func_name, &query_sig_params, "Promise<void>");
                let _ = writeln!(out, "\tawait sql`");
                let _ = writeln!(out, "    {}", sql_template);
                let _ = writeln!(out, "  `;");
                let _ = write!(out, "}}");
            }
            QueryCommand::ExecResult | QueryCommand::ExecRows => {
                let _ = writeln!(out, "/** Execute a query and return the number of affected rows. */");
                write_fn_sig(&mut out, &func_name, &query_sig_params, "Promise<number>");
                let _ = writeln!(out, "\tconst result = await sql`");
                let _ = writeln!(out, "    {}", sql_template);
                let _ = writeln!(out, "  `;");
                let _ = writeln!(out, "\treturn result.count;");
                let _ = write!(out, "}}");
            }
            QueryCommand::Grouped => {
                unreachable!("Grouped command is routed through generate_grouped_query_fn, not generate_query_fn")
            }
        }

        Ok(out)
    }

    fn generate_grouped_structs(
        &self,
        parent_struct_name: &str,
        child_struct_name: &str,
        parent_columns: &[ResolvedColumn],
        child_columns: &[ResolvedColumn],
        _key_column: &str,
    ) -> Result<String, ScytheError> {
        if self.js_mode {
            return Ok(generate_js_grouped_typedef_structs(
                child_struct_name,
                parent_struct_name,
                parent_columns,
                child_columns,
            ));
        }
        if self.row_type == TsRowType::Zod {
            return Ok(generate_zod_grouped_structs(
                child_struct_name,
                parent_struct_name,
                parent_columns,
                child_columns,
            ));
        }
        Ok(generate_grouped_interface_structs(
            child_struct_name,
            parent_struct_name,
            parent_columns,
            child_columns,
        ))
    }

    fn generate_grouped_query_fn(&self, request: &GroupedQueryFn<'_>) -> Result<String, ScytheError> {
        if self.js_mode {
            return self.generate_grouped_query_fn_js(request);
        }
        let analyzed = request.analyzed;
        let parent_struct_name = request.parent_struct_name;
        let child_struct_name = request.child_struct_name;
        let parent_columns = request.parent_columns;
        let child_columns = request.child_columns;
        let params = request.params;
        let key_column = request.key_column;

        if self.structs_only {
            return Ok(String::new());
        }

        let func_name = fn_name(&analyzed.name, &self.manifest.naming);
        let sql_clean = super::clean_sql_with_optional(&analyzed.sql, &analyzed.optional_params, &analyzed.params);
        let sql_clean = escape_ts_template_literal(&sql_clean);
        let name_map: std::collections::HashMap<u32, String> = analyzed
            .params
            .iter()
            .zip(params.iter())
            .map(|(ap, rp)| (ap.position as u32, rp.field_name.clone()))
            .collect();
        let sql_template = super::rewrite_pg_placeholders(&sql_clean, |n| {
            format!("${{{}}}", name_map.get(&n).map_or("?", |s| s.as_str()))
        });

        let param_list = params
            .iter()
            .map(|p| format!("{}: {}", p.field_name, p.full_type))
            .collect::<Vec<_>>()
            .join(", ");
        let inline_params = if params.is_empty() {
            "sql: Sql".to_string()
        } else {
            format!("sql: Sql, {}", param_list)
        };
        let ret = format!("Promise<{parent_struct_name}[]>");

        let mut out = String::new();
        let oneliner = format!("export async function {func_name}({inline_params}): {ret} {{");
        if oneliner.len() <= 80 {
            let _ = writeln!(out, "/** Fetch grouped {} rows. */", analyzed.name);
            let _ = writeln!(out, "{oneliner}");
        } else {
            let _ = writeln!(out, "/** Fetch grouped {} rows. */", analyzed.name);
            let _ = writeln!(out, "export async function {func_name}(");
            let _ = writeln!(out, "\tsql: Sql,");
            for p in params {
                let _ = writeln!(out, "\t{}: {},", p.field_name, p.full_type);
            }
            let _ = writeln!(out, "): {ret} {{");
        }

        let _ = writeln!(out, "\tconst flatRows = await sql<Record<string, unknown>[]>`");
        let _ = writeln!(out, "    {sql_template}");
        let _ = writeln!(out, "  `;");

        let fold = generate_ts_grouped_fold_body(
            parent_struct_name,
            child_struct_name,
            parent_columns,
            child_columns,
            key_column,
            false,
            |name, ty| format!("row['{name}'] as {ty}"),
        );
        out.push_str(&fold);
        let _ = write!(out, "}}");
        Ok(out)
    }

    fn generate_enum_def(&self, enum_info: &EnumInfo) -> Result<String, ScytheError> {
        if self.js_mode {
            return self.generate_enum_def_js(enum_info);
        }
        let type_name = enum_type_name(&enum_info.sql_name, &self.manifest.naming);
        if self.row_type == TsRowType::Zod {
            return Ok(generate_zod_enum(&type_name, &enum_info.values));
        }
        let mut out = String::new();
        let _ = writeln!(out, "export enum {} {{", type_name);
        for value in &enum_info.values {
            let variant = enum_variant_name(value, &self.manifest.naming);
            let _ = writeln!(out, "\t{} = \"{}\",", variant, value);
        }
        let _ = write!(out, "}}");
        Ok(out)
    }

    fn generate_composite_def(&self, composite: &CompositeInfo) -> Result<String, ScytheError> {
        if self.js_mode {
            return self.generate_composite_def_js(composite);
        }
        let name = to_pascal_case(&composite.sql_name);
        let mut out = String::new();
        let _ = writeln!(out, "/** Composite type {}. */", composite.sql_name);
        let _ = writeln!(out, "export interface {} {{", name);
        if composite.fields.is_empty() {
        } else {
            for field in &composite.fields {
                let ts_type = resolve_type(&field.neutral_type, &self.manifest, false)
                    .map(|t| t.into_owned())
                    .map_err(|e| {
                        ScytheError::new(ErrorCode::InternalError, format!("composite field type error: {}", e))
                    })?;
                let _ = writeln!(out, "\t{}: {};", to_camel_case(&field.name), ts_type);
            }
        }
        let _ = write!(out, "}}");
        Ok(out)
    }

    fn apply_options(&mut self, options: &std::collections::HashMap<String, String>) -> Result<(), ScytheError> {
        reject_unknown_options(
            &["row_type", "outer_join_unions", "structs_only", "field_case"],
            options,
        )?;

        if let Some(value) = options.get("row_type") {
            self.row_type = TsRowType::from_option(value)?;
        }
        if let Some(value) = options.get("outer_join_unions") {
            self.outer_join_unions = parse_bool_option("outer_join_unions", value)?;
        }
        if let Some(value) = options.get("structs_only") {
            self.structs_only = parse_bool_option("structs_only", value)?;
        }
        if let Some(value) = options.get("field_case") {
            self.field_case = TsFieldCase::from_option(value)?;
            // Keeps the central rename in `resolve.rs` (which reads this
            // string, not `TsFieldCase`) in sync with the runtime remap
            // decision above -- one option, one source of truth for both.
            self.manifest.naming.field_case = value.clone();
        }

        // See `TypescriptPgBackend::apply_options` for why these three are
        // rejected outright in JSDoc mode rather than silently ignored.
        if self.js_mode {
            if self.row_type == TsRowType::Zod {
                return Err(ScytheError::new(
                    ErrorCode::InternalError,
                    "javascript-postgres does not support row_type = \"zod\": the inferred `export type X = \
                     z.infer<...>` alias is TypeScript-only syntax a plain .js file cannot carry -- use \
                     typescript-postgres for Zod row types"
                        .to_string(),
                ));
            }
            if self.outer_join_unions {
                return Err(ScytheError::new(
                    ErrorCode::InternalError,
                    "javascript-postgres does not support outer_join_unions: the discriminated union is a \
                     TypeScript `type X = A & (B | C)` alias, which plain .js cannot carry -- use \
                     typescript-postgres"
                        .to_string(),
                ));
            }
            if self.field_case == TsFieldCase::Camel {
                return Err(ScytheError::new(
                    ErrorCode::InternalError,
                    "javascript-postgres does not support field_case = \"camelCase\": the field remap needs a \
                     TypeScript `as T` assertion, which plain .js cannot carry -- use typescript-postgres"
                        .to_string(),
                ));
            }
        }
        Ok(())
    }
}

impl TypescriptPostgresBackend {
    /// JSDoc-mode counterpart of `generate_query_fn` -- see
    /// `TypescriptPgBackend::generate_query_fn_js` for why `field_case =
    /// "camelCase"` needs no handling here.
    fn generate_query_fn_js(
        &self,
        analyzed: &AnalyzedQuery,
        struct_name: &str,
        params: &[ResolvedParam],
    ) -> Result<String, ScytheError> {
        if self.structs_only {
            return Ok(String::new());
        }

        const SQL_TYPE: &str = "import(\"postgres\").Sql";

        let func_name = fn_name(&analyzed.name, &self.manifest.naming);
        let mut out = String::new();

        let sql_clean = super::clean_sql_with_optional(&analyzed.sql, &analyzed.optional_params, &analyzed.params);
        let sql_clean = escape_ts_template_literal(&sql_clean);
        let name_map: std::collections::HashMap<u32, String> = analyzed
            .params
            .iter()
            .zip(params.iter())
            .map(|(ap, rp)| (ap.position as u32, rp.field_name.clone()))
            .collect();
        let sql_template = super::rewrite_pg_placeholders(&sql_clean, |n| {
            format!("${{{}}}", name_map.get(&n).map_or("?", |s| s.as_str()))
        });

        let query_sig_params: Vec<(String, String)> = std::iter::once(("sql".to_string(), SQL_TYPE.to_string()))
            .chain(params.iter().map(|p| (p.field_name.clone(), p.full_type.clone())))
            .collect();

        let write_signature = |out: &mut String, description: &str, sig_params: &[(String, String)], ret: &str| {
            out.push_str(&generate_jsdoc_fn_header(description, sig_params, ret));
            let _ = writeln!(out);
            let _ = writeln!(out, "{}", js_fn_signature_line(true, &func_name, sig_params));
        };

        match &analyzed.command {
            QueryCommand::One | QueryCommand::Opt => {
                write_signature(
                    &mut out,
                    &format!("Fetch a single {} or null.", struct_name),
                    &query_sig_params,
                    &format!("Promise<{} | null>", struct_name),
                );
                // postgres.js's `sql` tag defaults to its own untyped `Row`
                // shape without a type argument -- and unlike
                // `client.query(...)` (pg) or `pool.execute(...)` (mysql2),
                // that default is a *concrete* type, not `any`, so `rows[0]`
                // does not structurally match `StructName` and `tsc
                // --strict` rejects the assignment on `return`. The TS path
                // supplies `sql<StructName[]>` to fix this; JS mode has no
                // generic call syntax, so the JSDoc inline cast substitutes.
                let query_expr = format!("await sql`\n    {sql_template}\n  `");
                let _ = writeln!(
                    out,
                    "\tconst rows = {};",
                    js_type_cast(&format!("Array<{struct_name}>"), &query_expr)
                );
                let _ = writeln!(out, "\treturn rows[0] ?? null;");
                let _ = write!(out, "}}");
            }
            QueryCommand::Many => {
                write_signature(
                    &mut out,
                    &format!("Fetch all {} rows.", struct_name),
                    &query_sig_params,
                    &format!("Promise<{}[]>", struct_name),
                );
                let query_expr = format!("await sql`\n    {sql_template}\n  `");
                let _ = writeln!(
                    out,
                    "\tconst rows = {};",
                    js_type_cast(&format!("Array<{struct_name}>"), &query_expr)
                );
                let _ = writeln!(out, "\treturn rows;");
                let _ = write!(out, "}}");
            }
            QueryCommand::Exec => {
                write_signature(
                    &mut out,
                    "Execute a query returning no rows.",
                    &query_sig_params,
                    "Promise<void>",
                );
                let _ = writeln!(out, "\tawait sql`");
                let _ = writeln!(out, "    {}", sql_template);
                let _ = writeln!(out, "  `;");
                let _ = write!(out, "}}");
            }
            QueryCommand::ExecResult | QueryCommand::ExecRows => {
                write_signature(
                    &mut out,
                    "Execute a query and return the number of affected rows.",
                    &query_sig_params,
                    "Promise<number>",
                );
                let _ = writeln!(out, "\tconst result = await sql`");
                let _ = writeln!(out, "    {}", sql_template);
                let _ = writeln!(out, "  `;");
                let _ = writeln!(out, "\treturn result.count;");
                let _ = write!(out, "}}");
            }
            QueryCommand::Batch => {
                let batch_fn_name = format!("{}Batch", func_name);
                if params.len() > 1 {
                    let params_type_name = format!("{}BatchParams", struct_name);
                    let fields: Vec<(String, String)> = params
                        .iter()
                        .map(|p| (p.field_name.clone(), p.full_type.clone()))
                        .collect();
                    out.push_str(&generate_js_typedef(
                        &params_type_name,
                        &format!("Params for {} batch operation.", struct_name),
                        &fields,
                    ));
                    let _ = writeln!(out);
                    let _ = writeln!(out);
                    let batch_sig_params = vec![
                        ("sql".to_string(), SQL_TYPE.to_string()),
                        ("items".to_string(), format!("Array<{}>", params_type_name)),
                    ];
                    out.push_str(&generate_jsdoc_fn_header(
                        &format!(
                            "Execute {} for each item in the batch within a transaction.",
                            analyzed.name
                        ),
                        &batch_sig_params,
                        "Promise<void>",
                    ));
                    let _ = writeln!(out);
                    let _ = writeln!(out, "{}", js_fn_signature_line(true, &batch_fn_name, &batch_sig_params));
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (const item of items) {{");
                    let batch_sql = {
                        let mut s = sql_clean.clone();
                        let mut indexed: Vec<(i64, &str)> = analyzed
                            .params
                            .iter()
                            .zip(params.iter())
                            .map(|(ap, rp)| (ap.position, rp.field_name.as_str()))
                            .collect();
                        indexed.sort_by_key(|b| std::cmp::Reverse(b.0));
                        for (pos, field_name) in indexed {
                            let placeholder = format!("${}", pos);
                            let replacement = format!("${{item.{}}}", field_name);
                            s = s.replace(&placeholder, &replacement);
                        }
                        s
                    };
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", batch_sql);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                } else if params.len() == 1 {
                    let batch_sig_params = vec![
                        ("sql".to_string(), SQL_TYPE.to_string()),
                        ("items".to_string(), format!("Array<{}>", params[0].full_type)),
                    ];
                    out.push_str(&generate_jsdoc_fn_header(
                        &format!(
                            "Execute {} for each item in the batch within a transaction.",
                            analyzed.name
                        ),
                        &batch_sig_params,
                        "Promise<void>",
                    ));
                    let _ = writeln!(out);
                    let _ = writeln!(out, "{}", js_fn_signature_line(true, &batch_fn_name, &batch_sig_params));
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (const item of items) {{");
                    let batch_sql = sql_template.replace(&format!("${{{}}}", params[0].field_name), "${item}");
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", batch_sql);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                } else {
                    let batch_sig_params = vec![
                        ("sql".to_string(), SQL_TYPE.to_string()),
                        ("count".to_string(), "number".to_string()),
                    ];
                    out.push_str(&generate_jsdoc_fn_header(
                        &format!(
                            "Execute {} for each item in the batch within a transaction.",
                            analyzed.name
                        ),
                        &batch_sig_params,
                        "Promise<void>",
                    ));
                    let _ = writeln!(out);
                    let _ = writeln!(out, "{}", js_fn_signature_line(true, &batch_fn_name, &batch_sig_params));
                    let _ = writeln!(out, "\tawait sql.begin(async (tx) => {{");
                    let _ = writeln!(out, "\t\tfor (let i = 0; i < count; i++) {{");
                    let _ = writeln!(out, "\t\t\tawait tx`");
                    let _ = writeln!(out, "    {}", sql_template);
                    let _ = writeln!(out, "  `;");
                    let _ = writeln!(out, "\t\t}}");
                    let _ = writeln!(out, "\t}});");
                    let _ = write!(out, "}}");
                }
            }
            QueryCommand::Grouped => {
                unreachable!("Grouped command is routed through generate_grouped_query_fn, not generate_query_fn")
            }
        }

        Ok(out)
    }

    /// JSDoc-mode counterpart of `generate_grouped_query_fn`.
    fn generate_grouped_query_fn_js(&self, request: &GroupedQueryFn<'_>) -> Result<String, ScytheError> {
        let analyzed = request.analyzed;
        let parent_struct_name = request.parent_struct_name;
        let child_struct_name = request.child_struct_name;
        let parent_columns = request.parent_columns;
        let child_columns = request.child_columns;
        let params = request.params;
        let key_column = request.key_column;

        if self.structs_only {
            return Ok(String::new());
        }

        const SQL_TYPE: &str = "import(\"postgres\").Sql";

        let func_name = fn_name(&analyzed.name, &self.manifest.naming);
        let sql_clean = super::clean_sql_with_optional(&analyzed.sql, &analyzed.optional_params, &analyzed.params);
        let sql_clean = escape_ts_template_literal(&sql_clean);
        let name_map: std::collections::HashMap<u32, String> = analyzed
            .params
            .iter()
            .zip(params.iter())
            .map(|(ap, rp)| (ap.position as u32, rp.field_name.clone()))
            .collect();
        let sql_template = super::rewrite_pg_placeholders(&sql_clean, |n| {
            format!("${{{}}}", name_map.get(&n).map_or("?", |s| s.as_str()))
        });

        let sig_params: Vec<(String, String)> = std::iter::once(("sql".to_string(), SQL_TYPE.to_string()))
            .chain(params.iter().map(|p| (p.field_name.clone(), p.full_type.clone())))
            .collect();
        let ret = format!("Promise<{parent_struct_name}[]>");

        let mut out = String::new();
        out.push_str(&generate_jsdoc_fn_header(
            &format!("Fetch grouped {} rows.", analyzed.name),
            &sig_params,
            &ret,
        ));
        let _ = writeln!(out);
        let _ = writeln!(out, "{}", js_fn_signature_line(true, &func_name, &sig_params));

        let _ = writeln!(out, "\tconst flatRows = await sql`");
        let _ = writeln!(out, "    {sql_template}");
        let _ = writeln!(out, "  `;");

        let fold = generate_ts_grouped_fold_body(
            parent_struct_name,
            child_struct_name,
            parent_columns,
            child_columns,
            key_column,
            true,
            |name, _ty| format!("row['{name}']"),
        );
        out.push_str(&fold);
        let _ = write!(out, "}}");
        Ok(out)
    }

    /// JSDoc-mode counterpart of `generate_enum_def`.
    fn generate_enum_def_js(&self, enum_info: &EnumInfo) -> Result<String, ScytheError> {
        let type_name = enum_type_name(&enum_info.sql_name, &self.manifest.naming);
        let values_name = format!("{type_name}Values");
        let mut out = String::new();
        let _ = writeln!(out, "/** @type {{const}} */");
        let _ = writeln!(out, "export const {} = {{", values_name);
        for value in &enum_info.values {
            let variant = enum_variant_name(value, &self.manifest.naming);
            let _ = writeln!(out, "\t{}: \"{}\",", variant, value);
        }
        let _ = writeln!(out, "}};");
        let _ = writeln!(out);
        let _ = write!(
            out,
            "/** @typedef {{typeof {}[keyof typeof {}]}} {} */",
            values_name, values_name, type_name
        );
        Ok(out)
    }

    /// JSDoc-mode counterpart of `generate_composite_def`.
    fn generate_composite_def_js(&self, composite: &CompositeInfo) -> Result<String, ScytheError> {
        let name = to_pascal_case(&composite.sql_name);
        let mut fields = Vec::with_capacity(composite.fields.len());
        for field in &composite.fields {
            let ts_type = resolve_type(&field.neutral_type, &self.manifest, false)
                .map(|t| t.into_owned())
                .map_err(|e| {
                    ScytheError::new(ErrorCode::InternalError, format!("composite field type error: {}", e))
                })?;
            fields.push((to_camel_case(&field.name).into_owned(), ts_type));
        }
        Ok(generate_js_typedef(
            &name,
            &format!("Composite type {}.", composite.sql_name),
            &fields,
        ))
    }
}

#[cfg(test)]
mod tests {
    use super::TypescriptPostgresBackend;
    use crate::backend_trait::CodegenBackend;
    use scythe_core::analyzer::{AnalyzedColumn, AnalyzedParam, AnalyzedQuery, GroupByConfig};
    use scythe_core::parser::QueryCommand;

    fn discriminated_join_columns() -> Vec<crate::backend_trait::ResolvedColumn> {
        use crate::backend_trait::ResolvedColumn;
        vec![
            ResolvedColumn {
                name: "id".to_string(),
                field_name: "id".to_string(),
                lang_type: "number".to_string(),
                full_type: "number".to_string(),
                neutral_type: "int32".to_string(),
                sql_type: "int4".to_string(),
                nullable: false,
                join_group: None,
                nullable_before_join: false,
            },
            ResolvedColumn {
                name: "total".to_string(),
                field_name: "total".to_string(),
                lang_type: "string".to_string(),
                full_type: "string | null".to_string(),
                neutral_type: "decimal".to_string(),
                sql_type: "numeric".to_string(),
                nullable: true,
                join_group: Some("o".to_string()),
                nullable_before_join: false,
            },
        ]
    }

    #[test]
    fn test_zod_row_type_combined_with_outer_join_unions_emits_a_real_union_schema() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([
                ("row_type".to_string(), "zod".to_string()),
                ("outer_join_unions".to_string(), "true".to_string()),
            ]))
            .unwrap();

        let row_struct = backend
            .generate_row_struct("GetUserOrders", &discriminated_join_columns())
            .unwrap();

        assert!(
            row_struct.contains(".and(z.union(["),
            "must emit a real discriminated union; got:\n{row_struct}"
        );
    }

    #[test]
    fn test_zod_row_type_without_outer_join_unions_is_unchanged() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([(
                "row_type".to_string(),
                "zod".to_string(),
            )]))
            .unwrap();

        let row_struct = backend
            .generate_row_struct("GetUserOrders", &discriminated_join_columns())
            .unwrap();

        assert_eq!(
            row_struct,
            crate::backends::typescript_common::generate_zod_row_struct(
                "GetUserOrdersRow",
                "GetUserOrders",
                &discriminated_join_columns()
            )
        );
    }

    fn make_one_query(sql: &str, params: Vec<AnalyzedParam>) -> AnalyzedQuery {
        AnalyzedQuery::build(|aq| {
            aq.name = "GetUserById".to_string();
            aq.command = QueryCommand::One;
            aq.sql = sql.to_string();
            aq.columns = vec![AnalyzedColumn {
                name: "id".to_string(),
                neutral_type: "int32".to_string(),
                nullable: false,
                ..Default::default()
            }];
            aq.params = params;
            aq.deprecated = None;
            aq.source_table = None;
            aq.composites = vec![];
            aq.enums = vec![];
            aq.optional_params = vec![];
            aq.group_by = None;
            aq.custom = vec![];
        })
    }

    /// postgres.js's `sql` tag turns every `${}` into a live parameter
    /// binding, so a literal `${` surviving from the user's SQL would be
    /// misread as one. It must come out as inert escaped text while
    /// scythe's own binding for `$1` stays live.
    #[test]
    fn test_query_fn_escapes_user_dollar_brace_but_keeps_own_param_bindings_live() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_one_query(
            "SELECT id FROM users WHERE name = 'literal ${not_a_binding}' AND id = $1",
            vec![AnalyzedParam {
                name: "id".to_string(),
                neutral_type: "int32".to_string(),
                nullable: false,
                position: 1,
            }],
        );
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains(r"'literal \${not_a_binding}'"),
            "user's literal ${{}} must be escaped inert text; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("AND id = ${id}"),
            "scythe's own param binding must stay a live interpolation; got:\n{query_fn}"
        );
    }

    /// A literal backslash in the user's SQL must be doubled so it stays a
    /// single literal backslash in the generated JS template literal.
    #[test]
    fn test_query_fn_escapes_user_backslash_in_sql() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_one_query(r"SELECT id FROM users WHERE name = E'a\\b'", vec![]);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains(r"E'a\\\\b'"),
            "user backslash must be doubled; got:\n{query_fn}"
        );
    }

    /// A literal backtick in the user's SQL must not terminate the `sql`
    /// tag's template literal early.
    #[test]
    fn test_query_fn_escapes_user_backtick_in_sql() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_one_query("SELECT id FROM users WHERE name = `oops`", vec![]);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains(r"WHERE name = \`oops\`"),
            "user backtick must be escaped; got:\n{query_fn}"
        );
    }

    fn make_grouped_query() -> AnalyzedQuery {
        let parent_cols = vec![
            AnalyzedColumn {
                name: "id".to_string(),
                neutral_type: "int32".to_string(),
                nullable: false,
                ..Default::default()
            },
            AnalyzedColumn {
                name: "name".to_string(),
                neutral_type: "string".to_string(),
                nullable: false,
                ..Default::default()
            },
            AnalyzedColumn {
                name: "email".to_string(),
                neutral_type: "string".to_string(),
                nullable: false,
                ..Default::default()
            },
        ];
        let child_cols = vec![
            AnalyzedColumn {
                name: "order_id".to_string(),
                neutral_type: "int32".to_string(),
                nullable: false,
                ..Default::default()
            },
            AnalyzedColumn {
                name: "total".to_string(),
                neutral_type: "decimal".to_string(),
                nullable: true,
                ..Default::default()
            },
            AnalyzedColumn {
                name: "order_date".to_string(),
                neutral_type: "datetime".to_string(),
                nullable: false,
                ..Default::default()
            },
        ];
        let all_cols = [parent_cols.clone(), child_cols.clone()].concat();
        AnalyzedQuery::build(|aq| {
            aq.name = "GetUsersWithOrders".to_string();
            aq.command = QueryCommand::Grouped;
            aq.sql = "SELECT u.id, u.name, u.email, o.id AS order_id, o.total, o.created_at AS order_date\nFROM users u\nJOIN orders o ON o.user_id = u.id".to_string();
            aq.columns = all_cols;
            aq.params = vec![];
            aq.deprecated = None;
            aq.source_table = None;
            aq.composites = vec![];
            aq.enums = vec![];
            aq.optional_params = vec![];
            aq.group_by = Some(GroupByConfig {
                table: "users".to_string(),
                key_column: "id".to_string(),
                parent_columns: parent_cols,
                child_columns: child_cols,
            });
            aq.custom = vec![];
        })
    }

    #[test]
    fn test_grouped_typescript_postgres_structs() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_grouped_query();
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let row_struct = result.row_struct.as_deref().unwrap();

        assert!(
            row_struct.contains("interface GetUsersWithOrdersChildRow"),
            "missing child; got:\n{row_struct}"
        );
        assert!(
            row_struct.contains("order_id: number"),
            "child missing order_id; got:\n{row_struct}"
        );
        assert!(
            row_struct.contains("interface GetUsersWithOrdersRow"),
            "missing parent; got:\n{row_struct}"
        );
        assert!(
            row_struct.contains("children: GetUsersWithOrdersChildRow[]"),
            "missing children; got:\n{row_struct}"
        );
        let child_pos = row_struct.find("GetUsersWithOrdersChildRow").unwrap();
        let parent_pos = row_struct.find("interface GetUsersWithOrdersRow").unwrap();
        assert!(child_pos < parent_pos, "child must precede parent");
    }

    #[test]
    fn test_grouped_typescript_postgres_query_fn() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_grouped_query();
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(query_fn.contains("getUsersWithOrders"), "missing fn; got:\n{query_fn}");
        assert!(
            query_fn.contains("Promise<GetUsersWithOrdersRow[]>"),
            "wrong return type; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("sql<Record<string, unknown>[]>"),
            "must use typed sql template; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("new Map<unknown, GetUsersWithOrdersRow>()"),
            "must use Map; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("parent.children.push"),
            "must fold children; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("return result"),
            "must return result; got:\n{query_fn}"
        );
    }

    #[test]
    fn test_structs_only_suppresses_query_fn_and_driver_import() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([(
                "structs_only".to_string(),
                "true".to_string(),
            )]))
            .unwrap();

        let query = make_one_query("SELECT id FROM users WHERE id = $1", vec![]);
        let result = crate::generate_with_backend(&query, &backend).unwrap();

        assert_eq!(
            result.query_fn.as_deref(),
            Some(""),
            "structs_only must suppress the query function"
        );
        assert!(
            result
                .row_struct
                .as_deref()
                .unwrap()
                .contains("interface GetUserByIdRow"),
            "row struct must still be emitted"
        );

        let header = backend.file_header();
        assert!(
            !header.contains("postgres"),
            "the unused postgres driver import must be dropped; got:\n{header}"
        );
    }

    #[test]
    fn test_structs_only_unset_leaves_query_fn_present() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_one_query("SELECT id FROM users WHERE id = $1", vec![]);
        let result = crate::generate_with_backend(&query, &backend).unwrap();

        assert!(
            !result.query_fn.as_deref().unwrap().is_empty(),
            "without structs_only the query function must still be generated"
        );
        assert!(backend.file_header().contains("import type { Sql } from \"postgres\";"));
    }

    #[test]
    fn test_structs_only_rejects_invalid_value() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let result = backend.apply_options(&std::collections::HashMap::from([(
            "structs_only".to_string(),
            "maybe".to_string(),
        )]));
        assert!(result.is_err(), "expected 'maybe' to be rejected");
    }

    #[test]
    fn test_structs_only_combined_with_zod_row_type_keeps_zod_import_and_schema() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([
                ("structs_only".to_string(), "true".to_string()),
                ("row_type".to_string(), "zod".to_string()),
            ]))
            .unwrap();

        let query = make_one_query("SELECT id FROM users WHERE id = $1", vec![]);
        let result = crate::generate_with_backend(&query, &backend).unwrap();

        assert_eq!(result.query_fn.as_deref(), Some(""));
        assert!(
            result.row_struct.as_deref().unwrap().contains("z.object({"),
            "zod schema must still be emitted"
        );

        let header = backend.file_header();
        assert!(header.contains("import { z } from \"zod\";"), "got:\n{header}");
        assert!(!header.contains("postgres"), "got:\n{header}");
    }

    fn make_batch_query(name: &str, sql: &str, params: Vec<AnalyzedParam>) -> AnalyzedQuery {
        AnalyzedQuery::build(|aq| {
            aq.name = name.to_string();
            aq.command = QueryCommand::Batch;
            aq.sql = sql.to_string();
            aq.columns = vec![];
            aq.params = params;
            aq.deprecated = None;
            aq.source_table = None;
            aq.composites = vec![];
            aq.enums = vec![];
            aq.optional_params = vec![];
            aq.group_by = None;
            aq.custom = vec![];
        })
    }

    /// Regression test: `write_fn_sig`'s wrapped (>80 char) branch used to
    /// discard the `params_inline`/`sig_params` it was given and rebuild the
    /// signature from the outer per-column `params` slice instead. For a
    /// `:batch` function that slice is wrong -- the actual signature takes
    /// `items: XBatchParams[]`, not the raw columns -- so the emitted
    /// function declared parameters that didn't match its body (which
    /// references `items`). This must fail if that fallback is reinstated.
    #[test]
    fn test_batch_signature_wrap_declares_items_not_raw_columns() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_batch_query(
            "CreateUserAccountRecord",
            "INSERT INTO user_account_record (name, email) VALUES ($1, $2)",
            vec![
                AnalyzedParam {
                    name: "name".to_string(),
                    neutral_type: "string".to_string(),
                    nullable: false,
                    position: 1,
                },
                AnalyzedParam {
                    name: "email".to_string(),
                    neutral_type: "string".to_string(),
                    nullable: false,
                    position: 2,
                },
            ],
        );

        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("\titems: CreateUserAccountRecordRowBatchParams[],"),
            "wrapped batch signature must declare items with the batch params type; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains("\tname: string,") && !query_fn.contains("\temail: string,"),
            "wrapped batch signature must not fall back to the raw per-column params; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("for (const item of items)"),
            "every identifier the body references (items) must be declared in the signature; got:\n{query_fn}"
        );
    }

    /// Regression test guarding against a naive fix that splits
    /// `params_inline` on top-level `", "` to recover individual parameters.
    /// A `json` param's TS type is `Record<string, unknown>`, which itself
    /// contains `", "` -- splitting on it would corrupt a single parameter
    /// into `payload: Record<string` and `unknown>[]`. The structured
    /// `(name, type)` pairs must survive a wrapped signature intact.
    #[test]
    fn test_batch_signature_wrap_preserves_json_param_type_intact() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_batch_query(
            "CreateUserAccountRecordPayload",
            "INSERT INTO user_account_record_payload (payload) VALUES ($1)",
            vec![AnalyzedParam {
                name: "payload".to_string(),
                neutral_type: "json".to_string(),
                nullable: false,
                position: 1,
            }],
        );

        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("\titems: Record<string, unknown>[],"),
            "the json param's type must survive intact on the items line, not be split \
             on its internal ', '; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains("Record<string,\n"),
            "the json type must not be split at its internal comma; got:\n{query_fn}"
        );
    }

    fn make_query_with_snake_case_column(command: QueryCommand) -> AnalyzedQuery {
        AnalyzedQuery::build(|q| {
            q.name = "GetUserById".to_string();
            q.command = command;
            q.sql = "SELECT id, user_id FROM sessions WHERE id = $1".to_string();
            q.columns = vec![
                AnalyzedColumn {
                    name: "id".to_string(),
                    neutral_type: "int32".to_string(),
                    nullable: false,
                    ..Default::default()
                },
                AnalyzedColumn {
                    name: "user_id".to_string(),
                    neutral_type: "int32".to_string(),
                    nullable: false,
                    ..Default::default()
                },
            ];
            q.params = vec![];
            q.deprecated = None;
            q.source_table = None;
            q.composites = vec![];
            q.enums = vec![];
            q.optional_params = vec![];
            q.group_by = None;
            q.custom = vec![];
        })
    }

    /// This must fail before the fix: the `sql<StructName[]>` tag's generic
    /// is a type-level trust boundary only -- postgres.js still returns the
    /// driver's raw (snake_case) keys, so `field_case = "camelCase"`
    /// renaming the declared fields makes `tsc` believe the shape changed
    /// while every field reads back `undefined` at runtime.
    #[test]
    fn test_one_query_fn_remaps_fields_under_camel_case() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([(
                "field_case".to_string(),
                "camelCase".to_string(),
            )]))
            .unwrap();
        let query = make_query_with_snake_case_column(QueryCommand::One);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("sql<Record<string, unknown>[]>"),
            "must not trust the struct-typed generic; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("userId: row['user_id'] as number,"),
            "must remap the declared camelCase field from the driver's raw key; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains("sql<GetUserByIdRow[]>"),
            "must not use the old struct-typed generic under camelCase; got:\n{query_fn}"
        );
    }

    #[test]
    fn test_many_query_fn_remaps_fields_under_camel_case() {
        let mut backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        backend
            .apply_options(&std::collections::HashMap::from([(
                "field_case".to_string(),
                "camelCase".to_string(),
            )]))
            .unwrap();
        let query = make_query_with_snake_case_column(QueryCommand::Many);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("sql<Record<string, unknown>[]>"),
            "must not trust the struct-typed generic; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("return rows.map((row) => ({"),
            "must map each row; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("userId: row['user_id'] as number,"),
            "must remap the declared camelCase field from the driver's raw key; got:\n{query_fn}"
        );
    }

    #[test]
    fn test_one_query_fn_keeps_the_struct_generic_under_the_default_snake_case() {
        let backend = TypescriptPostgresBackend::new("postgresql").unwrap();
        let query = make_query_with_snake_case_column(QueryCommand::One);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("sql<GetUserByIdRow[]>"),
            "default field_case must keep the original struct-typed generic unchanged; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains("Record<string, unknown>"),
            "must not switch to the remap path under the default; got:\n{query_fn}"
        );
    }

    // -- javascript-postgres (JSDoc emit mode, #81) --------------------------

    fn js_backend() -> TypescriptPostgresBackend {
        TypescriptPostgresBackend::new_js("postgresql").unwrap()
    }

    fn resolved_columns_with_a_nullable_and_a_non_nullable_field() -> Vec<crate::backend_trait::ResolvedColumn> {
        use crate::backend_trait::ResolvedColumn;
        vec![
            ResolvedColumn {
                name: "id".to_string(),
                field_name: "id".to_string(),
                lang_type: "number".to_string(),
                full_type: "number".to_string(),
                neutral_type: "int32".to_string(),
                sql_type: "int4".to_string(),
                nullable: false,
                join_group: None,
                nullable_before_join: false,
            },
            ResolvedColumn {
                name: "bio".to_string(),
                field_name: "bio".to_string(),
                lang_type: "string".to_string(),
                full_type: "string | null".to_string(),
                neutral_type: "string".to_string(),
                sql_type: "text".to_string(),
                nullable: true,
                join_group: None,
                nullable_before_join: false,
            },
        ]
    }

    fn query_with_nullable_and_non_nullable_columns(command: QueryCommand) -> AnalyzedQuery {
        AnalyzedQuery::build(|q| {
            q.name = "GetUserById".to_string();
            q.command = command;
            q.sql = "SELECT id, bio FROM users WHERE id = $1".to_string();
            q.columns = vec![
                AnalyzedColumn {
                    name: "id".to_string(),
                    neutral_type: "int32".to_string(),
                    nullable: false,
                    ..Default::default()
                },
                AnalyzedColumn {
                    name: "bio".to_string(),
                    neutral_type: "string".to_string(),
                    nullable: true,
                    ..Default::default()
                },
            ];
            q.params = vec![AnalyzedParam {
                name: "id".to_string(),
                neutral_type: "int32".to_string(),
                nullable: false,
                position: 1,
            }];
            q.deprecated = None;
            q.source_table = None;
            q.composites = vec![];
            q.enums = vec![];
            q.optional_params = vec![];
            q.group_by = None;
            q.custom = vec![];
        })
    }

    #[test]
    fn test_js_mode_name_is_javascript_postgres() {
        assert_eq!(js_backend().name(), "javascript-postgres");
    }

    #[test]
    fn test_js_mode_file_header_has_no_ts_only_imports() {
        assert_eq!(js_backend().file_header(), "");
    }

    #[test]
    fn test_js_mode_row_struct_emits_nullable_column_as_type_or_null() {
        let backend = js_backend();
        let row_struct = backend
            .generate_row_struct(
                "GetUserById",
                &resolved_columns_with_a_nullable_and_a_non_nullable_field(),
            )
            .unwrap();

        assert!(
            row_struct.contains(" * @property {string | null} bio"),
            "nullable column must be `{{T | null}}`, never optional; got:\n{row_struct}"
        );
        assert!(row_struct.contains(" * @property {number} id"), "got:\n{row_struct}");
        assert!(!row_struct.contains("[bio]"), "{row_struct}");
        assert!(!row_struct.contains("bio?"), "{row_struct}");
    }

    #[test]
    fn test_js_mode_one_query_fn_is_plain_js_with_jsdoc_types() {
        let backend = js_backend();
        let query = query_with_nullable_and_non_nullable_columns(QueryCommand::One);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("@param {import(\"postgres\").Sql} sql"),
            "got:\n{query_fn}"
        );
        assert!(query_fn.contains("@param {number} id"), "got:\n{query_fn}");
        assert!(
            query_fn.contains("@returns {Promise<GetUserByIdRow | null>}"),
            "got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("export async function getUserById(sql, id) {"),
            "signature must have no type annotations; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains("sql<"),
            "must not use a TS generic type argument; got:\n{query_fn}"
        );
        assert!(
            !query_fn.contains(" as "),
            "must not use a TS `as` assertion; got:\n{query_fn}"
        );
        assert!(
            query_fn.contains("SELECT id, bio FROM users WHERE id = ${id}"),
            "got:\n{query_fn}"
        );
        // Regression: postgres.js's `sql` tag defaults to its own untyped
        // `Row` shape without a type argument -- that default is concrete,
        // not `any`, so `rows[0]` fails to structurally match
        // `GetUserByIdRow` under `tsc --strict` without this cast (verified
        // against real `tsc --checkJs --strict`).
        assert!(
            query_fn.contains("const rows = /** @type {Array<GetUserByIdRow>} */ (await sql`"),
            "got:\n{query_fn}"
        );
        assert!(query_fn.contains("return rows[0] ?? null;"), "got:\n{query_fn}");
    }

    #[test]
    fn test_js_mode_many_query_fn_returns_promise_array() {
        let backend = js_backend();
        let query = query_with_nullable_and_non_nullable_columns(QueryCommand::Many);
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(
            query_fn.contains("@returns {Promise<GetUserByIdRow[]>}"),
            "got:\n{query_fn}"
        );
        assert!(query_fn.contains("return rows;"), "got:\n{query_fn}");
        assert!(!query_fn.contains(" as "), "got:\n{query_fn}");
    }

    #[test]
    fn test_js_mode_exec_query_fn_returns_promise_void() {
        let backend = js_backend();
        let mut query = query_with_nullable_and_non_nullable_columns(QueryCommand::Exec);
        query.sql = "DELETE FROM users WHERE id = $1".to_string();
        let result = crate::generate_with_backend(&query, &backend).unwrap();
        let query_fn = result.query_fn.as_deref().unwrap();

        assert!(query_fn.contains("@returns {Promise<void>}"), "got:\n{query_fn}");
        assert!(
            query_fn.contains("export async function getUserById(sql, id) {"),
            "got:\n{query_fn}"
        );
    }

    #[test]
    fn test_js_mode_rejects_zod_row_type_and_camel_case_and_outer_join_unions() {
        for (key, value) in [
            ("row_type", "zod"),
            ("field_case", "camelCase"),
            ("outer_join_unions", "true"),
        ] {
            let mut backend = js_backend();
            let err = backend
                .apply_options(&std::collections::HashMap::from([(key.to_string(), value.to_string())]))
                .expect_err(&format!("javascript-postgres must reject {key} = {value}"));
            assert!(err.to_string().contains("javascript-postgres"), "{err}");
        }
    }
}