ironsbe-codegen 0.3.0

//! Enum and set code generation.

use ironsbe_schema::ir::{
    EnumVariant, SchemaIr, SetVariant, TypeKind, to_pascal_case, to_screaming_snake_case,
    to_snake_case,
};
use ironsbe_schema::types::PrimitiveType;

/// Generator for enum and set definitions.
pub struct EnumGenerator<'a> {
    ir: &'a SchemaIr,
}

impl<'a> EnumGenerator<'a> {
    /// Creates a new enum generator.
    #[must_use]
    pub fn new(ir: &'a SchemaIr) -> Self {
        Self { ir }
    }

    /// Generates all enum and set definitions.
    #[must_use]
    pub fn generate(&self) -> String {
        let mut output = String::new();

        for resolved_type in self.ir.types.values() {
            match &resolved_type.kind {
                TypeKind::Enum { encoding, variants } => {
                    output.push_str(&self.generate_enum(&resolved_type.name, *encoding, variants));
                }
                TypeKind::Set { encoding, choices } => {
                    output.push_str(&self.generate_set(&resolved_type.name, *encoding, choices));
                }
                _ => {}
            }
        }

        output
    }

    /// Generates an enum definition.
    fn generate_enum(
        &self,
        name: &str,
        encoding: PrimitiveType,
        variants: &[EnumVariant],
    ) -> String {
        let mut output = String::new();
        let rust_name = to_pascal_case(name);
        let rust_type = encoding.rust_type();

        output.push_str(&format!("/// {} enum.\n", rust_name));
        output.push_str("#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]\n");
        output.push_str(&format!("#[repr({})]\n", rust_type));
        output.push_str(&format!("pub enum {} {{\n", rust_name));

        // Generate enum variants from schema
        for variant in variants {
            let variant_name = to_pascal_case(&variant.name);
            output.push_str(&format!("    /// {} variant.\n", variant_name));
            output.push_str(&format!("    {} = {},\n", variant_name, variant.value));
        }

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

        // Implement From<primitive> -> Enum (safe match, no transmute)
        // Only generate if variants exist to avoid empty match
        if !variants.is_empty() {
            output.push_str(&format!("impl From<{}> for {} {{\n", rust_type, rust_name));
            output.push_str(&format!("    fn from(value: {}) -> Self {{\n", rust_type));
            output.push_str("        match value {\n");
            for variant in variants {
                let variant_name = to_pascal_case(&variant.name);
                output.push_str(&format!(
                    "            {} => Self::{},\n",
                    variant.value, variant_name
                ));
            }
            // Default to first variant for unknown values
            let first_name = to_pascal_case(&variants[0].name);
            output.push_str(&format!("            _ => Self::{},\n", first_name));
            output.push_str("        }\n");
            output.push_str("    }\n");
            output.push_str("}\n\n");
        }

        // Implement From<Enum> -> primitive
        if !variants.is_empty() {
            output.push_str(&format!("impl From<{}> for {} {{\n", rust_name, rust_type));
            output.push_str(&format!("    fn from(value: {}) -> Self {{\n", rust_name));
            output.push_str("        value as Self\n");
            output.push_str("    }\n");
            output.push_str("}\n\n");
        }

        output
    }

    /// Generates a set (bitfield) definition.
    fn generate_set(&self, name: &str, encoding: PrimitiveType, choices: &[SetVariant]) -> String {
        let mut output = String::new();
        let rust_name = to_pascal_case(name);
        let rust_type = encoding.rust_type();

        output.push_str(&format!("/// {} bitfield set.\n", rust_name));
        output.push_str("#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]\n");
        output.push_str(&format!("pub struct {}({});\n\n", rust_name, rust_type));

        output.push_str(&format!("impl {} {{\n", rust_name));

        // Generate bit position constants for each choice
        for choice in choices {
            let const_name = to_screaming_snake_case(&choice.name);
            output.push_str(&format!(
                "    /// Bit position for {} choice.\n",
                choice.name
            ));
            output.push_str(&format!(
                "    pub const {}: u8 = {};\n",
                const_name, choice.bit_position
            ));
        }
        if !choices.is_empty() {
            output.push('\n');
        }

        output.push_str(&format!("    /// Creates a new empty {}.\n", rust_name));
        output.push_str("    #[must_use]\n");
        output.push_str("    pub const fn new() -> Self {\n");
        output.push_str("        Self(0)\n");
        output.push_str("    }\n\n");

        output.push_str(&format!("    /// Creates from raw {} value.\n", rust_type));
        output.push_str("    #[must_use]\n");
        output.push_str(&format!(
            "    pub const fn from_raw(value: {}) -> Self {{\n",
            rust_type
        ));
        output.push_str("        Self(value)\n");
        output.push_str("    }\n\n");

        output.push_str("    /// Returns the raw value.\n");
        output.push_str("    #[must_use]\n");
        output.push_str(&format!(
            "    pub const fn raw(&self) -> {} {{\n",
            rust_type
        ));
        output.push_str("        self.0\n");
        output.push_str("    }\n\n");

        output.push_str("    /// Checks if a bit is set.\n");
        output.push_str("    #[must_use]\n");
        output.push_str("    pub const fn is_set(&self, bit: u8) -> bool {\n");
        output.push_str("        (self.0 >> bit) & 1 != 0\n");
        output.push_str("    }\n\n");

        output.push_str("    /// Sets a bit.\n");
        output.push_str("    pub fn set(&mut self, bit: u8) {\n");
        output.push_str("        self.0 |= 1 << bit;\n");
        output.push_str("    }\n\n");

        output.push_str("    /// Clears a bit.\n");
        output.push_str("    pub fn clear(&mut self, bit: u8) {\n");
        output.push_str("        self.0 &= !(1 << bit);\n");
        output.push_str("    }\n");

        // Generate named methods for each choice
        for choice in choices {
            let method_name = to_snake_case(&choice.name);
            output.push_str(&format!("\n    /// Checks if {} is set.\n", choice.name));
            output.push_str("    #[must_use]\n");
            output.push_str(&format!(
                "    pub const fn is_{}(&self) -> bool {{\n",
                method_name
            ));
            output.push_str(&format!("        self.is_set({})\n", choice.bit_position));
            output.push_str("    }\n");

            output.push_str(&format!("\n    /// Sets {}.\n", choice.name));
            output.push_str(&format!("    pub fn set_{}(&mut self) {{\n", method_name));
            output.push_str(&format!("        self.set({});\n", choice.bit_position));
            output.push_str("    }\n");

            output.push_str(&format!("\n    /// Clears {}.\n", choice.name));
            output.push_str(&format!("    pub fn clear_{}(&mut self) {{\n", method_name));
            output.push_str(&format!("        self.clear({});\n", choice.bit_position));
            output.push_str("    }\n");
        }

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

        output
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use ironsbe_schema::ir::SchemaIr;
    use ironsbe_schema::parser::parse_schema;

    fn create_test_ir_with_enum() -> SchemaIr {
        let xml = r#"<?xml version="1.0" encoding="UTF-8"?>
<sbe:messageSchema xmlns:sbe="http://fixprotocol.io/2016/sbe"
                   package="test" id="1" version="1" byteOrder="littleEndian">
    <types>
        <enum name="Side" encodingType="uint8">
            <validValue name="Buy">1</validValue>
            <validValue name="Sell">2</validValue>
        </enum>
    </types>
    <sbe:message name="Test" id="1" blockLength="1">
        <field name="side" id="1" type="Side" offset="0"/>
    </sbe:message>
</sbe:messageSchema>"#;

        let schema = parse_schema(xml).expect("Failed to parse");
        SchemaIr::from_schema(&schema)
    }

    fn create_test_ir_with_set() -> SchemaIr {
        let xml = r#"<?xml version="1.0" encoding="UTF-8"?>
<sbe:messageSchema xmlns:sbe="http://fixprotocol.io/2016/sbe"
                   package="test" id="1" version="1" byteOrder="littleEndian">
    <types>
        <set name="Flags" encodingType="uint8">
            <choice name="Active">0</choice>
            <choice name="Visible">1</choice>
        </set>
    </types>
    <sbe:message name="Test" id="1" blockLength="1">
        <field name="flags" id="1" type="Flags" offset="0"/>
    </sbe:message>
</sbe:messageSchema>"#;

        let schema = parse_schema(xml).expect("Failed to parse");
        SchemaIr::from_schema(&schema)
    }

    #[test]
    fn test_enum_generator_new() {
        let ir = create_test_ir_with_enum();
        let generator = EnumGenerator::new(&ir);
        assert!(!generator.ir.types.is_empty());
    }

    #[test]
    fn test_generate_enum() {
        let ir = create_test_ir_with_enum();
        let generator = EnumGenerator::new(&ir);
        let output = generator.generate();

        // Check enum structure
        assert!(output.contains("pub enum Side"));
        assert!(output.contains("Buy = 1"));
        assert!(output.contains("Sell = 2"));

        // Check From impl with match arms
        assert!(output.contains("impl From<u8> for Side"));
        assert!(output.contains("1 => Self::Buy"));
        assert!(output.contains("2 => Self::Sell"));
        assert!(output.contains("_ => Self::Buy")); // fallback to first variant
    }

    #[test]
    fn test_generate_set() {
        let ir = create_test_ir_with_set();
        let generator = EnumGenerator::new(&ir);
        let output = generator.generate();

        // Check struct and basic methods
        assert!(output.contains("struct"));
        assert!(output.contains("is_set"));
        assert!(output.contains("set"));
        assert!(output.contains("clear"));

        // Check specific bit position constants are generated
        assert!(
            output.contains("pub const ACTIVE: u8 = 0"),
            "Should generate ACTIVE constant with bit position 0"
        );
        assert!(
            output.contains("pub const VISIBLE: u8 = 1"),
            "Should generate VISIBLE constant with bit position 1"
        );

        // Check specific named methods are generated
        assert!(
            output.contains("fn is_active(&self)"),
            "Should generate is_active method"
        );
        assert!(
            output.contains("fn set_active(&mut self)"),
            "Should generate set_active method"
        );
        assert!(
            output.contains("fn clear_active(&mut self)"),
            "Should generate clear_active method"
        );
    }

    #[test]
    fn test_generate_empty_ir() {
        let xml = r#"<?xml version="1.0" encoding="UTF-8"?>
<sbe:messageSchema xmlns:sbe="http://fixprotocol.io/2016/sbe"
                   package="test" id="1" version="1" byteOrder="littleEndian">
    <types>
        <type name="uint64" primitiveType="uint64"/>
    </types>
    <sbe:message name="Test" id="1" blockLength="8">
        <field name="value" id="1" type="uint64" offset="0"/>
    </sbe:message>
</sbe:messageSchema>"#;

        let schema = parse_schema(xml).expect("Failed to parse");
        let ir = SchemaIr::from_schema(&schema);
        let generator = EnumGenerator::new(&ir);
        let output = generator.generate();

        // No enums or sets, should be empty or minimal
        assert!(!output.contains("enum Side"));
    }
}