prax-orm-cli 0.9.4

//! `prax generate` command - Generate Rust client code from schema.

use std::collections::{HashMap, HashSet};
use std::path::{Path, PathBuf};

use crate::cli::GenerateArgs;
use crate::config::{CONFIG_FILE_NAME, Config, SCHEMA_FILE_PATH};
use crate::error::{CliError, CliResult};
use crate::output::{self, success};

/// Run the generate command
pub async fn run(args: GenerateArgs) -> CliResult<()> {
    output::header("Generate Prax Client");

    let cwd = std::env::current_dir()?;

    // Load config
    let config_path = cwd.join(CONFIG_FILE_NAME);
    let config = if config_path.exists() {
        Config::load(&config_path)?
    } else {
        Config::default()
    };

    // Resolve schema path
    let schema_path = args
        .schema
        .clone()
        .unwrap_or_else(|| cwd.join(SCHEMA_FILE_PATH));
    if !schema_path.exists() {
        return Err(CliError::Config(format!(
            "Schema file not found: {}",
            schema_path.display()
        )));
    }

    // Resolve output directory
    let output_dir = args
        .output
        .clone()
        .unwrap_or_else(|| PathBuf::from(&config.generator.output));

    output::kv("Schema", &schema_path.display().to_string());
    output::kv("Output", &output_dir.display().to_string());
    output::newline();

    output::step(1, 4, "Reading schema...");

    // Parse schema
    let schema_content = std::fs::read_to_string(&schema_path)?;
    let schema = parse_schema(&schema_content)?;

    output::step(2, 4, "Validating schema...");

    // Validate schema
    validate_schema(&schema)?;

    output::step(3, 4, "Generating code...");

    // Create output directory
    std::fs::create_dir_all(&output_dir)?;

    // Generate code
    let generated_files = generate_code(&schema, &output_dir, &args, &config)?;

    output::step(4, 4, "Writing files...");

    // Print generated files
    output::newline();
    output::section("Generated files");

    for file in &generated_files {
        let relative_path = file
            .strip_prefix(&cwd)
            .unwrap_or(file)
            .display()
            .to_string();
        output::list_item(&relative_path);
    }

    output::newline();
    success(&format!(
        "Generated {} files in {:.2}s",
        generated_files.len(),
        0.0 // TODO: Add timing
    ));

    Ok(())
}

/// Parse and validate the schema file
fn parse_schema(content: &str) -> CliResult<prax_schema::Schema> {
    // Use validate_schema to ensure field types are properly resolved
    // (e.g., FieldType::Model -> FieldType::Enum for enum references)
    prax_schema::validate_schema(content)
        .map_err(|e| CliError::Schema(format!("Failed to parse/validate schema: {}", e)))
}

/// Validate the schema (now a no-op since parse_schema does validation)
fn validate_schema(_schema: &prax_schema::Schema) -> CliResult<()> {
    // Validation is now done in parse_schema via validate_schema()
    Ok(())
}

/// Generate code from the schema
fn generate_code(
    schema: &prax_schema::ast::Schema,
    output_dir: &Path,
    args: &GenerateArgs,
    config: &Config,
) -> CliResult<Vec<PathBuf>> {
    let mut generated_files = Vec::new();

    // Determine which features to generate
    let features = if !args.features.is_empty() {
        args.features.clone()
    } else {
        config
            .generator
            .features
            .clone()
            .unwrap_or_else(|| vec!["client".to_string()])
    };

    // Build relation graph for cycle detection
    let relation_graph = build_relation_graph(schema);

    // Generate main client module
    let client_path = output_dir.join("mod.rs");
    let client_code = generate_client_module(schema, &features)?;
    std::fs::write(&client_path, client_code)?;
    generated_files.push(client_path);

    // Generate model modules
    for model in schema.models.values() {
        let model_path = output_dir.join(format!("{}.rs", to_snake_case(model.name())));
        let model_code = generate_model_module(model, &features, &relation_graph)?;
        std::fs::write(&model_path, model_code)?;
        generated_files.push(model_path);
    }

    // Generate enum modules
    for enum_def in schema.enums.values() {
        let enum_path = output_dir.join(format!("{}.rs", to_snake_case(enum_def.name())));
        let enum_code = generate_enum_module(enum_def)?;
        std::fs::write(&enum_path, enum_code)?;
        generated_files.push(enum_path);
    }

    // Generate type definitions
    let types_path = output_dir.join("types.rs");
    let types_code = generate_types_module(schema)?;
    std::fs::write(&types_path, types_code)?;
    generated_files.push(types_path);

    // Generate filters
    let filters_path = output_dir.join("filters.rs");
    let filters_code = generate_filters_module(schema)?;
    std::fs::write(&filters_path, filters_code)?;
    generated_files.push(filters_path);

    Ok(generated_files)
}

/// Build a graph of model relations for cycle detection.
/// Returns a map from model name to the set of model names it references
/// (non-list relations only, since Vec<T> doesn't cause infinite size).
fn build_relation_graph(schema: &prax_schema::ast::Schema) -> HashMap<String, HashSet<String>> {
    let mut graph: HashMap<String, HashSet<String>> = HashMap::new();

    for model in schema.models.values() {
        let entry = graph.entry(model.name().to_string()).or_default();
        for field in model.fields.values() {
            if let prax_schema::ast::FieldType::Model(ref target) = field.field_type
                && !field.is_list()
            {
                entry.insert(target.to_string());
            }
        }
    }

    graph
}

/// Check if a non-list relation field from `source_model` to `target_model`
/// participates in a cycle (i.e. target_model can reach source_model through
/// non-list relations). If so, the field must be wrapped in Box<T>.
fn needs_boxing(
    source_model: &str,
    target_model: &str,
    graph: &HashMap<String, HashSet<String>>,
) -> bool {
    let mut visited = HashSet::new();
    let mut stack = vec![target_model.to_string()];

    while let Some(current) = stack.pop() {
        if current == source_model {
            return true;
        }
        if !visited.insert(current.clone()) {
            continue;
        }
        if let Some(neighbors) = graph.get(&current) {
            for neighbor in neighbors {
                stack.push(neighbor.clone());
            }
        }
    }

    false
}

/// Generate the main client module
fn generate_client_module(
    schema: &prax_schema::ast::Schema,
    _features: &[String],
) -> CliResult<String> {
    let mut code = String::new();

    code.push_str("//! Auto-generated by Prax - DO NOT EDIT\n");
    code.push_str("//!\n");
    code.push_str("//! This module contains the generated Prax client.\n\n");

    // Module declarations
    code.push_str("pub mod types;\n");
    code.push_str("pub mod filters;\n\n");

    for model in schema.models.values() {
        code.push_str(&format!("pub mod {};\n", to_snake_case(model.name())));
    }

    for enum_def in schema.enums.values() {
        code.push_str(&format!("pub mod {};\n", to_snake_case(enum_def.name())));
    }

    code.push('\n');

    // Re-exports
    code.push_str("#[allow(unused_imports)]\npub use types::*;\n");
    code.push_str("#[allow(unused_imports)]\npub use filters::*;\n\n");

    for model in schema.models.values() {
        code.push_str(&format!(
            "#[allow(unused_imports)]\npub use {}::{};\n",
            to_snake_case(model.name()),
            model.name()
        ));
    }

    for enum_def in schema.enums.values() {
        code.push_str(&format!(
            "#[allow(unused_imports)]\npub use {}::{};\n",
            to_snake_case(enum_def.name()),
            enum_def.name()
        ));
    }

    code.push('\n');

    // Client struct with Clone bound and derive
    code.push_str("#[allow(dead_code)]\n");
    code.push_str("/// The Prax database client\n");
    code.push_str("#[derive(Clone)]\n");
    code.push_str("pub struct PraxClient<E: prax_query::QueryEngine> {\n");
    code.push_str("    engine: E,\n");
    code.push_str("}\n\n");

    code.push_str("impl<E: prax_query::QueryEngine> PraxClient<E> {\n");
    code.push_str("    /// Create a new Prax client with the given query engine\n");
    code.push_str("    pub fn new(engine: E) -> Self {\n");
    code.push_str("        Self { engine }\n");
    code.push_str("    }\n\n");

    code.push_str("    /// Borrow the underlying engine. Useful when composing\n");
    code.push_str("    /// per-model operations directly or running raw SQL.\n");
    code.push_str("    pub fn engine(&self) -> &E {\n");
    code.push_str("        &self.engine\n");
    code.push_str("    }\n\n");

    code.push_str("    /// Execute a typed raw SQL query, decoding each returned\n");
    code.push_str("    /// row as `T`. Mirrors `prax_orm::PraxClient::query_raw`.\n");
    code.push_str("    ///\n");
    code.push_str("    /// The typed per-model API covers the common CRUD cases;\n");
    code.push_str("    /// use this for window functions, vendor-specific\n");
    code.push_str("    /// extensions, CTEs, JOIN-driven row shapes, and aggregates\n");
    code.push_str("    /// that the fluent builder doesn't model yet. `T` must\n");
    code.push_str("    /// implement both `Model` (for the table association) and\n");
    code.push_str("    /// `FromRow` (for row decoding); the generator emits both\n");
    code.push_str("    /// impls on every model in this client.\n");
    code.push_str("    pub async fn query_raw<T>(&self, sql: prax_query::raw::Sql)\n");
    code.push_str("        -> prax_query::error::QueryResult<Vec<T>>\n");
    code.push_str("    where\n");
    code.push_str(
        "        T: prax_query::traits::Model + prax_query::row::FromRow + Send + 'static,\n",
    );
    code.push_str("    {\n");
    code.push_str("        let (s, p) = sql.build();\n");
    code.push_str("        self.engine.query_many::<T>(&s, p).await\n");
    code.push_str("    }\n\n");

    code.push_str("    /// Execute a raw statement that doesn't return rows\n");
    code.push_str("    /// (INSERT / UPDATE / DELETE / DDL). Returns the\n");
    code.push_str("    /// driver-reported affected-row count. Mirrors\n");
    code.push_str("    /// `prax_orm::PraxClient::execute_raw`.\n");
    code.push_str("    pub async fn execute_raw(&self, sql: prax_query::raw::Sql)\n");
    code.push_str("        -> prax_query::error::QueryResult<u64>\n");
    code.push_str("    {\n");
    code.push_str("        let (s, p) = sql.build();\n");
    code.push_str("        self.engine.execute_raw(&s, p).await\n");
    code.push_str("    }\n\n");

    for model in schema.models.values() {
        let snake_name = to_snake_case(model.name());
        code.push_str(&format!("    /// Access {} operations\n", model.name()));
        code.push_str(&format!(
            "    pub fn {}(&self) -> {}::Client<E> {{\n",
            snake_name, snake_name,
        ));
        code.push_str(&format!(
            "        {}::Client::new(self.engine.clone())\n",
            snake_name,
        ));
        code.push_str("    }\n\n");
    }

    code.push_str("}\n");

    Ok(code)
}

/// Generate a model module
fn generate_model_module(
    model: &prax_schema::ast::Model,
    features: &[String],
    relation_graph: &HashMap<String, HashSet<String>>,
) -> CliResult<String> {
    let mut code = String::new();

    code.push_str(&format!(
        "//! Auto-generated module for {} model\n\n",
        model.name()
    ));

    // Import sibling types for relation fields
    code.push_str("#[allow(unused_imports)]\n");
    code.push_str("use super::*;\n");
    code.push_str("#[allow(unused_imports)]\n");
    code.push_str("use prax_query::traits::Model;\n\n");

    // Derive macros based on features
    let mut derives = vec!["Debug", "Clone"];
    if features.contains(&"serde".to_string()) {
        derives.push("serde::Serialize");
        derives.push("serde::Deserialize");
    }

    // Model struct
    code.push_str("#[allow(dead_code)]\n");
    code.push_str(&format!("#[derive({})]\n", derives.join(", ")));
    code.push_str(&format!("pub struct {} {{\n", model.name()));

    for field in model.fields.values() {
        let field_name = to_field_ident(field.name());

        // Add serde rename if mapped
        if let Some(attr) = field.get_attribute("map")
            && features.contains(&"serde".to_string())
            && let Some(value) = attr.first_arg().and_then(|v| v.as_string())
        {
            code.push_str(&format!("    #[serde(rename = \"{}\")]\n", value));
        }

        let rust_type = field_type_to_rust_with_boxing(
            &field.field_type,
            field.modifier,
            model.name(),
            relation_graph,
        );
        code.push_str(&format!("    pub {}: {},\n", field_name, rust_type));
    }

    code.push_str("}\n\n");

    // Model trait implementation
    let table_name = model.table_name();
    let id_fields: Vec<&str> = model.id_fields().iter().map(|f| f.name()).collect();
    let scalar_columns: Vec<String> = model
        .scalar_fields()
        .iter()
        .map(|f| {
            // Use @map name if present, otherwise snake_case the field name
            f.get_attribute("map")
                .and_then(|a| a.first_arg())
                .and_then(|v| v.as_string())
                .map(|s| s.to_string())
                .unwrap_or_else(|| to_snake_case(f.name()))
        })
        .collect();

    code.push_str(&format!("impl Model for {} {{\n", model.name()));
    code.push_str(&format!(
        "    const MODEL_NAME: &'static str = \"{}\";\n",
        model.name()
    ));
    code.push_str(&format!(
        "    const TABLE_NAME: &'static str = \"{}\";\n",
        table_name
    ));
    code.push_str(&format!(
        "    const PRIMARY_KEY: &'static [&'static str] = &[{}];\n",
        id_fields
            .iter()
            .map(|f| format!("\"{}\"", to_snake_case(f)))
            .collect::<Vec<_>>()
            .join(", ")
    ));
    code.push_str(&format!(
        "    const COLUMNS: &'static [&'static str] = &[{}];\n",
        scalar_columns
            .iter()
            .map(|c| format!("\"{}\"", c))
            .collect::<Vec<_>>()
            .join(", ")
    ));
    code.push_str("}\n\n");

    // FromRow — required to decode rows back into the model when an
    // operation is run. Mirrors the emission in
    // `prax-codegen/src/generators/derive_from_row.rs`: scalar fields
    // decode via `FromColumn`; relation fields default-init and are
    // filled later by the relation executor on the `.include` path.
    code.push_str(&format!(
        "impl prax_query::row::FromRow for {} {{\n",
        model.name()
    ));
    code.push_str(
        "    fn from_row(row: &impl prax_query::row::RowRef)\n        -> Result<Self, prax_query::row::RowError>\n    {\n",
    );
    code.push_str("        Ok(Self {\n");
    for field in model.fields.values() {
        let field_name = to_field_ident(field.name());
        let rust_type = field_type_to_rust_with_boxing(
            &field.field_type,
            field.modifier,
            model.name(),
            relation_graph,
        );
        if field.is_relation() {
            code.push_str(&format!(
                "            {}: ::core::default::Default::default(),\n",
                field_name
            ));
        } else {
            let column = field
                .get_attribute("map")
                .and_then(|a| a.first_arg())
                .and_then(|v| v.as_string())
                .map(|s| s.to_string())
                .unwrap_or_else(|| field_name.clone());
            code.push_str(&format!(
                "            {}: <{} as prax_query::row::FromColumn>::from_column(row, \"{}\")?,\n",
                field_name, rust_type, column
            ));
        }
    }
    code.push_str("        })\n");
    code.push_str("    }\n");
    code.push_str("}\n\n");

    // ModelWithPk — required by composite-key handling and by operations
    // that need to extract the primary key from a model instance (e.g.
    // upsert, nested writes). Mirrors
    // `prax-codegen/src/generators/derive_model_with_pk.rs`.
    code.push_str(&format!(
        "impl prax_query::traits::ModelWithPk for {} {{\n",
        model.name()
    ));
    code.push_str("    fn pk_value(&self) -> prax_query::filter::FilterValue {\n");
    let id_field_objs: Vec<_> = model.id_fields();
    if id_field_objs.len() == 1 {
        let f = id_field_objs[0];
        code.push_str(&format!(
            "        <{} as prax_query::filter::ToFilterValue>::to_filter_value(&self.{})\n",
            field_type_to_rust_with_boxing(&f.field_type, f.modifier, model.name(), relation_graph),
            to_field_ident(f.name())
        ));
    } else if id_field_objs.is_empty() {
        code.push_str("        prax_query::filter::FilterValue::Null\n");
    } else {
        code.push_str("        prax_query::filter::FilterValue::List(vec![\n");
        for f in &id_field_objs {
            code.push_str(&format!(
                "            <{} as prax_query::filter::ToFilterValue>::to_filter_value(&self.{}),\n",
                field_type_to_rust_with_boxing(&f.field_type, f.modifier, model.name(), relation_graph),
                to_field_ident(f.name())
            ));
        }
        code.push_str("        ])\n");
    }
    code.push_str("    }\n\n");

    code.push_str(
        "    fn get_column_value(&self, column: &str)\n        -> ::core::option::Option<prax_query::filter::FilterValue>\n    {\n",
    );
    code.push_str("        match column {\n");
    for field in model.scalar_fields() {
        // Rust field identifier — escape reserved keywords.
        let field_name = to_field_ident(field.name());
        // SQL column name — use raw snake_case (no r# prefix) because the
        // @map override or fallback feeds a string literal passed to
        // `FromColumn::from_column(row, "...")`, not an identifier.
        let column = field
            .get_attribute("map")
            .and_then(|a| a.first_arg())
            .and_then(|v| v.as_string())
            .map(|s| s.to_string())
            .unwrap_or_else(|| to_snake_case(field.name()));
        let rust_type = field_type_to_rust_with_boxing(
            &field.field_type,
            field.modifier,
            model.name(),
            relation_graph,
        );
        code.push_str(&format!(
            "            \"{}\" => ::core::option::Option::Some(\n                <{} as prax_query::filter::ToFilterValue>::to_filter_value(&self.{})\n            ),\n",
            column, rust_type, field_name
        ));
    }
    code.push_str("            _ => ::core::option::Option::None,\n");
    code.push_str("        }\n");
    code.push_str("    }\n");
    code.push_str("}\n\n");

    // Per-model `Client<E>` (named `Client`, not `{Model}Operations`, so
    // `prax::client!(Foo, Bar, ...)` can find `foo::Client::new(...)`
    // and `bar::Client::new(...)` by snake-cased module path — matching
    // the shape emitted by `#[derive(Model)]`).
    code.push_str("#[allow(dead_code)]\n");
    code.push_str(&format!("/// Operations for the {} model\n", model.name()));
    code.push_str("pub struct Client<E: prax_query::QueryEngine> {\n");
    code.push_str("    engine: E,\n");
    code.push_str("}\n\n");

    code.push_str("impl<E: prax_query::QueryEngine> Client<E> {\n");
    code.push_str("    pub fn new(engine: E) -> Self {\n");
    code.push_str("        Self { engine }\n");
    code.push_str("    }\n\n");

    let model_ty = model.name();
    let crud_methods: &[(&str, &str, &str)] = &[
        ("find_many", "FindManyOperation", "Find many records"),
        ("find_unique", "FindUniqueOperation", "Find a unique record"),
        (
            "find_first",
            "FindFirstOperation",
            "Find the first matching record",
        ),
        ("create", "CreateOperation", "Create a new record"),
        (
            "create_many",
            "CreateManyOperation",
            "Create many records in one operation",
        ),
        ("update", "UpdateOperation", "Update a record"),
        (
            "update_many",
            "UpdateManyOperation",
            "Update many records matching a filter",
        ),
        ("upsert", "UpsertOperation", "Insert or update a record"),
        ("delete", "DeleteOperation", "Delete a record"),
        (
            "delete_many",
            "DeleteManyOperation",
            "Delete many records matching a filter",
        ),
        ("count", "CountOperation", "Count records"),
    ];
    for (method, op_ty, doc) in crud_methods {
        code.push_str(&format!("    /// {}\n", doc));
        code.push_str(&format!(
            "    pub fn {}(&self) -> prax_query::operations::{}<E, {}> {{\n",
            method, op_ty, model_ty,
        ));
        code.push_str(&format!(
            "        prax_query::operations::{}::new(self.engine.clone())\n",
            op_ty,
        ));
        code.push_str("    }\n\n");
    }

    code.push_str("}\n");

    Ok(code)
}

/// Generate an enum module
fn generate_enum_module(enum_def: &prax_schema::ast::Enum) -> CliResult<String> {
    let mut code = String::new();

    code.push_str(&format!(
        "//! Auto-generated module for {} enum\n\n",
        enum_def.name()
    ));

    code.push_str("#[allow(dead_code)]\n");
    code.push_str(
        "#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]\n",
    );
    code.push_str(&format!("pub enum {} {{\n", enum_def.name()));

    for variant in &enum_def.variants {
        let raw_name = variant.name();
        let pascal_name = to_pascal_case(raw_name);

        // Check for explicit @map attribute first
        if let Some(attr) = variant.attributes.iter().find(|a| a.is("map"))
            && let Some(value) = attr.first_arg().and_then(|v| v.as_string())
        {
            code.push_str(&format!("    #[serde(rename = \"{}\")]\n", value));
            code.push_str(&format!("    {},\n", pascal_name));
            continue;
        }

        // If variant name differs from PascalCase form, add serde rename
        if raw_name != pascal_name {
            code.push_str(&format!("    #[serde(rename = \"{}\")]\n", raw_name));
        }
        code.push_str(&format!("    {},\n", pascal_name));
    }

    code.push_str("}\n\n");

    // Display implementation for SQL serialization
    code.push_str(&format!(
        "impl std::fmt::Display for {} {{\n",
        enum_def.name()
    ));
    code.push_str("    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {\n");
    code.push_str("        match self {\n");
    for variant in &enum_def.variants {
        let raw_name = variant.name();
        let pascal_name = to_pascal_case(raw_name);
        let db_value = variant.db_value();
        code.push_str(&format!(
            "            Self::{} => write!(f, \"{}\"),\n",
            pascal_name, db_value
        ));
    }
    code.push_str("        }\n");
    code.push_str("    }\n");
    code.push_str("}\n\n");

    // Default implementation
    if let Some(default_variant) = enum_def.variants.first() {
        let pascal_name = to_pascal_case(default_variant.name());
        code.push_str(&format!("impl Default for {} {{\n", enum_def.name()));
        code.push_str(&format!(
            "    fn default() -> Self {{\n        Self::{}\n    }}\n",
            pascal_name
        ));
        code.push_str("}\n\n");
    }

    // Round-trip helper: parse the DB string form back into an enum variant.
    // Used by the `FromColumn` impls below and callable directly by
    // consumers that need to deserialize a raw string payload.
    code.push_str(&format!(
        "impl std::str::FromStr for {} {{\n",
        enum_def.name()
    ));
    code.push_str("    type Err = prax_query::row::RowError;\n");
    code.push_str("    fn from_str(s: &str) -> Result<Self, Self::Err> {\n");
    code.push_str("        match s {\n");
    for variant in &enum_def.variants {
        let raw_name = variant.name();
        let pascal_name = to_pascal_case(raw_name);
        let db_value = variant.db_value();
        code.push_str(&format!(
            "            \"{}\" => Ok(Self::{}),\n",
            db_value, pascal_name
        ));
    }
    code.push_str(&format!(
        "            _ => Err(prax_query::row::RowError::TypeConversion {{\n                column: String::new(),\n                message: format!(\"unknown {} variant: {{}}\", s),\n            }}),\n",
        enum_def.name()
    ));
    code.push_str("        }\n");
    code.push_str("    }\n");
    code.push_str("}\n\n");

    // `FromColumn` — decode a string column back into the enum. Required
    // for `find_many` / `find_unique` / any query that returns rows with
    // this enum as a field type.
    code.push_str(&format!(
        "impl prax_query::row::FromColumn for {} {{\n",
        enum_def.name()
    ));
    code.push_str(
        "    fn from_column(row: &impl prax_query::row::RowRef, column: &str)\n        -> Result<Self, prax_query::row::RowError>\n    {\n",
    );
    code.push_str("        let raw = row.get_string(column)?;\n");
    code.push_str("        <Self as std::str::FromStr>::from_str(&raw).map_err(|e| {\n");
    code.push_str("            let msg = match &e {\n");
    code.push_str(
        "                prax_query::row::RowError::TypeConversion { message, .. } => message.clone(),\n",
    );
    code.push_str("                other => other.to_string(),\n");
    code.push_str("            };\n");
    code.push_str("            prax_query::row::RowError::TypeConversion {\n");
    code.push_str("                column: column.to_string(),\n");
    code.push_str("                message: msg,\n");
    code.push_str("            }\n");
    code.push_str("        })\n");
    code.push_str("    }\n");
    code.push_str("}\n\n");

    // `Option<Enum>` handled by the blanket `impl<T: FromColumn>
    // FromColumn for Option<T>` in prax-query — no per-enum Option impl
    // needed here (the orphan rule would forbid it on the consumer side
    // anyway).

    // `ToFilterValue` — encode the enum as a string FilterValue so that
    // `where` clauses / `ModelWithPk::pk_value` / nested writes can send
    // it as a bind parameter.
    code.push_str(&format!(
        "impl prax_query::filter::ToFilterValue for {} {{\n",
        enum_def.name()
    ));
    code.push_str("    fn to_filter_value(&self) -> prax_query::filter::FilterValue {\n");
    code.push_str("        prax_query::filter::FilterValue::String(self.to_string())\n");
    code.push_str("    }\n");
    code.push_str("}\n");

    Ok(code)
}

/// Generate types module
fn generate_types_module(schema: &prax_schema::ast::Schema) -> CliResult<String> {
    let mut code = String::new();

    code.push_str("//! Common type definitions\n\n");
    code.push_str("#[allow(unused_imports)]\npub use chrono::{DateTime, Utc};\n");
    code.push_str("#[allow(unused_imports)]\npub use uuid::Uuid;\n");
    code.push_str("#[allow(unused_imports)]\npub use serde_json::Value as Json;\n");
    code.push('\n');

    // Add any custom types from composite types
    for composite in schema.types.values() {
        code.push_str("#[allow(dead_code)]\n");
        code.push_str("#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]\n");
        code.push_str(&format!("pub struct {} {{\n", composite.name()));
        for field in composite.fields.values() {
            let rust_type = field_type_to_rust(&field.field_type, field.modifier);
            let field_name = to_field_ident(field.name());
            code.push_str(&format!("    pub {}: {},\n", field_name, rust_type));
        }
        code.push_str("}\n\n");
    }

    Ok(code)
}

/// Generate filters module
fn generate_filters_module(schema: &prax_schema::ast::Schema) -> CliResult<String> {
    let mut code = String::new();

    code.push_str("//! Filter types for queries\n\n");
    code.push_str("#[allow(unused_imports)]\n");
    code.push_str("use prax_query::filter::{Filter, ScalarFilter};\n");

    // Collect all enum types referenced by model scalar fields
    let mut referenced_enums = HashSet::new();
    for model in schema.models.values() {
        for field in model.fields.values() {
            if !field.is_relation()
                && let prax_schema::ast::FieldType::Enum(ref name) = field.field_type
            {
                referenced_enums.insert(name.to_string());
            }
        }
    }

    // Import enum types
    for enum_name in &referenced_enums {
        code.push_str(&format!(
            "#[allow(unused_imports)]\nuse super::{}::{};\n",
            to_snake_case(enum_name),
            enum_name
        ));
    }

    code.push('\n');

    for model in schema.models.values() {
        // Where input
        code.push_str("#[allow(dead_code)]\n");
        code.push_str(&format!("/// Filter input for {} queries\n", model.name()));
        code.push_str("#[derive(Debug, Default, Clone)]\n");
        code.push_str(&format!("pub struct {}WhereInput {{\n", model.name()));

        for field in model.fields.values() {
            if !field.is_relation() {
                let filter_type = field_to_filter_type(&field.field_type);
                let field_name = to_field_ident(field.name());
                code.push_str(&format!(
                    "    pub {}: Option<{}>,\n",
                    field_name, filter_type
                ));
            }
        }

        code.push_str("    pub and: Option<Vec<Self>>,\n");
        code.push_str("    pub or: Option<Vec<Self>>,\n");
        code.push_str("    pub not: Option<Box<Self>>,\n");
        code.push_str("}\n\n");

        // OrderBy input
        code.push_str("#[allow(dead_code)]\n");
        code.push_str(&format!(
            "/// Order by input for {} queries\n",
            model.name()
        ));
        code.push_str("#[derive(Debug, Default, Clone)]\n");
        code.push_str(&format!("pub struct {}OrderByInput {{\n", model.name()));

        for field in model.fields.values() {
            if !field.is_relation() {
                let field_name = to_field_ident(field.name());
                code.push_str(&format!(
                    "    pub {}: Option<prax_query::SortOrder>,\n",
                    field_name
                ));
            }
        }

        code.push_str("}\n\n");
    }

    Ok(code)
}

/// Convert a field type to Rust type (basic, without boxing)
fn field_type_to_rust(
    field_type: &prax_schema::ast::FieldType,
    modifier: prax_schema::ast::TypeModifier,
) -> String {
    use prax_schema::ast::{FieldType, ScalarType, TypeModifier};

    let base_type = match field_type {
        FieldType::Scalar(scalar) => match scalar {
            ScalarType::Int => "i32".to_string(),
            ScalarType::BigInt => "i64".to_string(),
            ScalarType::Float => "f64".to_string(),
            ScalarType::String => "String".to_string(),
            ScalarType::Boolean => "bool".to_string(),
            ScalarType::DateTime => "chrono::DateTime<chrono::Utc>".to_string(),
            ScalarType::Date => "chrono::NaiveDate".to_string(),
            ScalarType::Time => "chrono::NaiveTime".to_string(),
            ScalarType::Json => "serde_json::Value".to_string(),
            ScalarType::Bytes => "Vec<u8>".to_string(),
            ScalarType::Decimal => "rust_decimal::Decimal".to_string(),
            ScalarType::Uuid => "uuid::Uuid".to_string(),
            ScalarType::Cuid => "String".to_string(),
            ScalarType::Cuid2 => "String".to_string(),
            ScalarType::NanoId => "String".to_string(),
            ScalarType::Ulid => "String".to_string(),
            ScalarType::Vector(_) | ScalarType::HalfVector(_) => "Vec<f32>".to_string(),
            ScalarType::SparseVector(_) => "Vec<(u32, f32)>".to_string(),
            ScalarType::Bit(_) => "Vec<u8>".to_string(),
        },
        FieldType::Model(name) => name.to_string(),
        FieldType::Enum(name) => name.to_string(),
        FieldType::Composite(name) => name.to_string(),
        FieldType::Unsupported(_) => "serde_json::Value".to_string(),
    };

    match modifier {
        TypeModifier::Optional | TypeModifier::OptionalList => format!("Option<{}>", base_type),
        TypeModifier::List => format!("Vec<{}>", base_type),
        TypeModifier::Required => base_type,
    }
}

/// Convert a field type to Rust type with Box<T> wrapping for cyclic relations.
fn field_type_to_rust_with_boxing(
    field_type: &prax_schema::ast::FieldType,
    modifier: prax_schema::ast::TypeModifier,
    source_model: &str,
    relation_graph: &HashMap<String, HashSet<String>>,
) -> String {
    use prax_schema::ast::{FieldType, TypeModifier};

    // For model references (non-list), check if boxing is needed to break cycles.
    // Non-list relations are always emitted as `Option<T>` regardless of the
    // schema's required/optional modifier: the relation is "not loaded" until
    // `.include` populates it, so the Rust struct must allow representing the
    // un-included state. This also gives the field a `Default::default()`
    // (== `None`), which `FromRow` relies on to construct a row that hasn't
    // been join-decoded yet. The schema-level required-ness is a database
    // constraint enforced by FK + NOT NULL, not a Rust struct invariant.
    if let FieldType::Model(target) = field_type
        && !matches!(modifier, TypeModifier::List)
    {
        let should_box = needs_boxing(source_model, target, relation_graph);
        let base = target.to_string();
        return if should_box {
            format!("Option<Box<{}>>", base)
        } else {
            format!("Option<{}>", base)
        };
    }

    // Fallback to basic conversion for non-cyclic fields
    field_type_to_rust(field_type, modifier)
}

/// Convert a field type to filter type
fn field_to_filter_type(field_type: &prax_schema::ast::FieldType) -> String {
    use prax_schema::ast::{FieldType, ScalarType};

    match field_type {
        FieldType::Scalar(scalar) => match scalar {
            ScalarType::Int | ScalarType::BigInt => "ScalarFilter<i64>".to_string(),
            ScalarType::Float | ScalarType::Decimal => "ScalarFilter<f64>".to_string(),
            ScalarType::String
            | ScalarType::Uuid
            | ScalarType::Cuid
            | ScalarType::Cuid2
            | ScalarType::NanoId
            | ScalarType::Ulid => "ScalarFilter<String>".to_string(),
            ScalarType::Boolean => "ScalarFilter<bool>".to_string(),
            ScalarType::DateTime => "ScalarFilter<chrono::DateTime<chrono::Utc>>".to_string(),
            ScalarType::Date => "ScalarFilter<chrono::NaiveDate>".to_string(),
            ScalarType::Time => "ScalarFilter<chrono::NaiveTime>".to_string(),
            ScalarType::Json => "ScalarFilter<serde_json::Value>".to_string(),
            ScalarType::Bytes => "ScalarFilter<Vec<u8>>".to_string(),
            // pgvector scalars. Only `VectorFilter` exists in prax-pgvector
            // today (for `vector(N)` and `halfvec(N)`); sparse and bit
            // columns fall back to the raw element type under
            // `ScalarFilter` until dedicated filter types ship upstream.
            // Fully qualify the path so the generated filters.rs compiles
            // without requiring the consumer to add a `use` statement.
            ScalarType::Vector(_) | ScalarType::HalfVector(_) => {
                "prax_pgvector::filter::VectorFilter".to_string()
            }
            ScalarType::SparseVector(_) => "ScalarFilter<Vec<(u32, f32)>>".to_string(),
            ScalarType::Bit(_) => "ScalarFilter<Vec<u8>>".to_string(),
        },
        FieldType::Enum(name) => format!("ScalarFilter<{}>", name),
        _ => "Filter".to_string(),
    }
}

/// Convert PascalCase to snake_case
fn to_snake_case(name: &str) -> String {
    let mut result = String::new();
    for (i, c) in name.chars().enumerate() {
        if c.is_uppercase() {
            if i > 0 {
                result.push('_');
            }
            result.push(c.to_lowercase().next().unwrap());
        } else {
            result.push(c);
        }
    }
    result
}

/// Snake-case a name and escape it as a raw identifier if the result
/// collides with a Rust reserved keyword. Use for any emitted Rust field
/// or variable name; plain column-name strings (serde rename values, SQL
/// column lookups) still use `to_snake_case` directly.
///
/// Schemas with columns literally named `type`, `match`, `use`, `loop`,
/// etc. (common in Prisma — documents, notifications, email_verification
/// all have a `type` column) otherwise produce code like `pub type: …`
/// that fails to parse. This function emits `r#type` instead.
///
/// The four keywords Rust forbids as raw identifiers (`crate`, `self`,
/// `Self`, `super`) are intentionally not escaped; a column literally
/// named `self` would still fail to compile, which is the correct
/// behavior (the schema should be fixed).
fn to_field_ident(name: &str) -> String {
    let snake = to_snake_case(name);
    if is_rust_keyword(&snake) {
        format!("r#{}", snake)
    } else {
        snake
    }
}

fn is_rust_keyword(s: &str) -> bool {
    matches!(
        s,
        "abstract"
            | "as"
            | "async"
            | "await"
            | "become"
            | "box"
            | "break"
            | "const"
            | "continue"
            | "do"
            | "dyn"
            | "else"
            | "enum"
            | "extern"
            | "false"
            | "final"
            | "fn"
            | "for"
            | "gen"
            | "if"
            | "impl"
            | "in"
            | "let"
            | "loop"
            | "macro"
            | "match"
            | "mod"
            | "move"
            | "mut"
            | "override"
            | "priv"
            | "pub"
            | "ref"
            | "return"
            | "static"
            | "struct"
            | "trait"
            | "true"
            | "try"
            | "type"
            | "typeof"
            | "unsafe"
            | "unsized"
            | "use"
            | "virtual"
            | "where"
            | "while"
            | "yield"
    )
}

/// Convert snake_case, SCREAMING_SNAKE_CASE, or any other casing to PascalCase.
fn to_pascal_case(name: &str) -> String {
    if name.is_empty() {
        return String::new();
    }

    // If already PascalCase (starts with uppercase, contains lowercase), return as-is
    let first = name.chars().next().unwrap();
    if first.is_uppercase() && name.chars().any(|c| c.is_lowercase()) && !name.contains('_') {
        return name.to_string();
    }

    // Split on underscores and capitalize each segment
    name.split('_')
        .filter(|s| !s.is_empty())
        .map(|segment| {
            let mut chars = segment.chars();
            match chars.next() {
                None => String::new(),
                Some(first) => {
                    let rest: String = chars.collect();
                    format!("{}{}", first.to_uppercase(), rest.to_lowercase())
                }
            }
        })
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_to_snake_case() {
        assert_eq!(to_snake_case("BoardMember"), "board_member");
        assert_eq!(to_snake_case("User"), "user");
        assert_eq!(to_snake_case("JiraImportConfig"), "jira_import_config");
    }

    #[test]
    fn test_to_pascal_case_from_snake() {
        assert_eq!(to_pascal_case("card_created"), "CardCreated");
        assert_eq!(to_pascal_case("branch_deleted"), "BranchDeleted");
        assert_eq!(to_pascal_case("pr_merged"), "PrMerged");
    }

    #[test]
    fn test_to_pascal_case_from_screaming() {
        assert_eq!(to_pascal_case("CARD_CREATED"), "CardCreated");
        assert_eq!(to_pascal_case("PR_MERGED"), "PrMerged");
    }

    #[test]
    fn test_to_pascal_case_already_pascal() {
        assert_eq!(to_pascal_case("Admin"), "Admin");
        assert_eq!(to_pascal_case("SuperAdmin"), "SuperAdmin");
        assert_eq!(to_pascal_case("Low"), "Low");
    }

    #[test]
    fn test_to_pascal_case_single_word() {
        assert_eq!(to_pascal_case("active"), "Active");
        assert_eq!(to_pascal_case("ACTIVE"), "Active");
    }

    #[test]
    fn test_needs_boxing_direct_cycle() {
        let mut graph = HashMap::new();
        graph.insert(
            "Board".to_string(),
            HashSet::from(["JiraConfig".to_string()]),
        );
        graph.insert(
            "JiraConfig".to_string(),
            HashSet::from(["Board".to_string()]),
        );

        assert!(needs_boxing("Board", "JiraConfig", &graph));
        assert!(needs_boxing("JiraConfig", "Board", &graph));
    }

    #[test]
    fn test_needs_boxing_no_cycle() {
        let mut graph = HashMap::new();
        graph.insert("Post".to_string(), HashSet::from(["User".to_string()]));
        graph.insert("User".to_string(), HashSet::new());

        assert!(!needs_boxing("Post", "User", &graph));
    }

    #[test]
    fn test_needs_boxing_indirect_cycle() {
        let mut graph = HashMap::new();
        graph.insert("A".to_string(), HashSet::from(["B".to_string()]));
        graph.insert("B".to_string(), HashSet::from(["C".to_string()]));
        graph.insert("C".to_string(), HashSet::from(["A".to_string()]));

        assert!(needs_boxing("A", "B", &graph));
        assert!(needs_boxing("B", "C", &graph));
        assert!(needs_boxing("C", "A", &graph));
    }
}