use std::fmt::Write;
use std::path::Path;
use scythe_backend::manifest::{BackendManifest, load_manifest};
use scythe_backend::naming::{
enum_type_name, enum_variant_name, fn_name, row_struct_name, to_pascal_case,
};
use scythe_backend::types::resolve_type;
use scythe_core::analyzer::{AnalyzedQuery, CompositeInfo, EnumInfo};
use scythe_core::errors::{ErrorCode, ScytheError};
use scythe_core::parser::QueryCommand;
use crate::backend_trait::{CodegenBackend, ResolvedColumn, ResolvedParam};
const DEFAULT_MANIFEST_TOML: &str = include_str!("../../manifests/csharp-npgsql.toml");
pub struct CsharpNpgsqlBackend {
manifest: BackendManifest,
}
impl CsharpNpgsqlBackend {
pub fn new() -> Result<Self, ScytheError> {
let manifest_path = Path::new("backends/csharp-npgsql/manifest.toml");
let manifest = if manifest_path.exists() {
load_manifest(manifest_path)
.map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
} else {
toml::from_str(DEFAULT_MANIFEST_TOML)
.map_err(|e| ScytheError::new(ErrorCode::InternalError, format!("manifest: {e}")))?
};
Ok(Self { manifest })
}
pub fn manifest(&self) -> &BackendManifest {
&self.manifest
}
}
fn reader_method(neutral_type: &str) -> &'static str {
match neutral_type {
"bool" => "GetBoolean",
"int16" => "GetInt16",
"int32" => "GetInt32",
"int64" => "GetInt64",
"float32" => "GetFloat",
"float64" => "GetDouble",
"string" | "json" | "inet" | "interval" => "GetString",
"uuid" => "GetGuid",
"decimal" => "GetDecimal",
"date" => "GetFieldValue<DateOnly>",
"time" | "time_tz" => "GetFieldValue<TimeOnly>",
"datetime" => "GetDateTime",
"datetime_tz" => "GetFieldValue<DateTimeOffset>",
_ => "GetValue",
}
}
fn rewrite_params(sql: &str) -> String {
let mut result = sql.to_string();
for i in (1..=99).rev() {
let from = format!("${}", i);
let to = format!("@p{}", i);
result = result.replace(&from, &to);
}
result
}
impl CodegenBackend for CsharpNpgsqlBackend {
fn name(&self) -> &str {
"csharp-npgsql"
}
fn generate_row_struct(
&self,
query_name: &str,
columns: &[ResolvedColumn],
) -> Result<String, ScytheError> {
let struct_name = row_struct_name(query_name, &self.manifest.naming);
let mut out = String::new();
let _ = writeln!(out, "public record {}(", struct_name);
for (i, c) in columns.iter().enumerate() {
let field = to_pascal_case(&c.field_name);
let sep = if i + 1 < columns.len() { "," } else { "" };
let _ = writeln!(out, " {} {}{}", c.full_type, field, sep);
}
let _ = write!(out, ");");
Ok(out)
}
fn generate_model_struct(
&self,
table_name: &str,
columns: &[ResolvedColumn],
) -> Result<String, ScytheError> {
let name = to_pascal_case(table_name);
self.generate_row_struct(&name, columns)
}
fn generate_query_fn(
&self,
analyzed: &AnalyzedQuery,
struct_name: &str,
columns: &[ResolvedColumn],
params: &[ResolvedParam],
) -> Result<String, ScytheError> {
let func_name = fn_name(&analyzed.name, &self.manifest.naming);
let sql = rewrite_params(&super::clean_sql(&analyzed.sql));
let mut out = String::new();
let param_list = params
.iter()
.map(|p| format!("{} {}", p.full_type, p.field_name))
.collect::<Vec<_>>()
.join(", ");
let sep = if param_list.is_empty() { "" } else { ", " };
let return_type = match &analyzed.command {
QueryCommand::One => format!("{}?", struct_name),
QueryCommand::Many | QueryCommand::Batch => {
format!("List<{}>", struct_name)
}
QueryCommand::Exec => "void".to_string(),
QueryCommand::ExecResult | QueryCommand::ExecRows => "int".to_string(),
};
let is_async_void = return_type == "void";
let task_type = if is_async_void {
"Task".to_string()
} else {
format!("Task<{}>", return_type)
};
let _ = writeln!(
out,
"public static async {} {}(NpgsqlConnection conn{}{}) {{",
task_type, func_name, sep, param_list
);
let _ = writeln!(
out,
" await using var cmd = new NpgsqlCommand(\"{}\", conn);",
sql
);
for (i, p) in params.iter().enumerate() {
let _ = writeln!(
out,
" cmd.Parameters.AddWithValue(\"p{}\", {});",
i + 1,
p.field_name
);
}
match &analyzed.command {
QueryCommand::One => {
let _ = writeln!(
out,
" await using var reader = await cmd.ExecuteReaderAsync();"
);
let _ = writeln!(out, " if (!await reader.ReadAsync()) return null;");
let _ = writeln!(out, " return new {}(", struct_name);
for (i, col) in columns.iter().enumerate() {
let method = reader_method(&col.neutral_type);
let sep = if i + 1 < columns.len() { "," } else { "" };
if col.nullable {
let _ = writeln!(
out,
" reader.IsDBNull({i}) ? null : reader.{method}({i}){sep}"
);
} else {
let _ = writeln!(out, " reader.{method}({i}){sep}");
}
}
let _ = writeln!(out, " );");
}
QueryCommand::Many | QueryCommand::Batch => {
let _ = writeln!(
out,
" await using var reader = await cmd.ExecuteReaderAsync();"
);
let _ = writeln!(out, " var results = new List<{}>();", struct_name);
let _ = writeln!(out, " while (await reader.ReadAsync()) {{");
let _ = writeln!(out, " results.Add(new {}(", struct_name);
for (i, col) in columns.iter().enumerate() {
let method = reader_method(&col.neutral_type);
let sep = if i + 1 < columns.len() { "," } else { "" };
if col.nullable {
let _ = writeln!(
out,
" reader.IsDBNull({i}) ? null : reader.{method}({i}){sep}"
);
} else {
let _ = writeln!(out, " reader.{method}({i}){sep}");
}
}
let _ = writeln!(out, " ));");
let _ = writeln!(out, " }}");
let _ = writeln!(out, " return results;");
}
QueryCommand::Exec => {
let _ = writeln!(out, " await cmd.ExecuteNonQueryAsync();");
}
QueryCommand::ExecResult | QueryCommand::ExecRows => {
let _ = writeln!(out, " return await cmd.ExecuteNonQueryAsync();");
}
}
let _ = write!(out, "}}");
Ok(out)
}
fn generate_enum_def(&self, enum_info: &EnumInfo) -> Result<String, ScytheError> {
let type_name = enum_type_name(&enum_info.sql_name, &self.manifest.naming);
let mut out = String::new();
let _ = writeln!(out, "public enum {} {{", type_name);
for value in &enum_info.values {
let variant = enum_variant_name(value, &self.manifest.naming);
let _ = writeln!(out, " {},", variant);
}
let _ = write!(out, "}}");
Ok(out)
}
fn generate_composite_def(&self, composite: &CompositeInfo) -> Result<String, ScytheError> {
let name = to_pascal_case(&composite.sql_name);
let mut out = String::new();
if composite.fields.is_empty() {
let _ = writeln!(out, "public record {}();", name);
} else {
let _ = writeln!(out, "public record {}(", name);
for (i, field) in composite.fields.iter().enumerate() {
let cs_type = resolve_type(&field.neutral_type, &self.manifest, false)
.map(|t| t.into_owned())
.unwrap_or_else(|_| "object".to_string());
let field_name = to_pascal_case(&field.name);
let sep = if i + 1 < composite.fields.len() {
","
} else {
""
};
let _ = writeln!(out, " {} {}{}", cs_type, field_name, sep);
}
let _ = write!(out, ");");
}
Ok(out)
}
}