ryo-suggest 0.1.0

//! SpecGenerator - Generate code from Spec definitions
//!
//! This module provides Spec-first code generation, complementing the
//! problem-detection approach of Suggest.
//!
//! # Architecture
//!
//! ```text
//! ┌─────────────────────────────────────────────────────────────────┐
//! │  Suggest (Problem Detection)    vs    SpecGenerator (Creation)  │
//! │  ────────────────────────────────────────────────────────────── │
//! │  Code → detect() → Problems       Spec → generate() → New Code  │
//! └─────────────────────────────────────────────────────────────────┘
//! ```
//!
//! # Usage
//!
//! ```ignore
//! use ryo_suggest::spec::{SpecGenerator, DomainSpecGenerator};
//!
//! let generator = DomainSpecGenerator::new();
//! let specs = generator.generate(&ctx, &spec_alias_data);
//! // specs: Vec<MutationSpec> containing AddField, AddMethod, etc.
//! ```

use ryo_analysis::context::AnalysisContext;
use ryo_analysis::query::SpecAliasData;
use ryo_analysis::{SymbolId, SymbolKind};
use ryo_executor::{SelfParam, Visibility};

use crate::MutationSpec;

/// Trait for generating code from Spec definitions
///
/// Unlike `Suggest` which detects problems in existing code,
/// `SpecGenerator` creates new code based on Spec definitions.
pub trait SpecGenerator: Send + Sync {
    /// Generator name for identification
    fn name(&self) -> &'static str;

    /// Description of what this generator creates
    fn description(&self) -> &str;

    /// Check if this generator applies to the given Spec
    fn matches(&self, spec: &SpecAliasData) -> bool;

    /// Generate MutationSpecs from a Spec definition
    ///
    /// Returns structured MutationSpecs (AddField, AddMethod, etc.)
    /// rather than raw code strings when possible.
    fn generate(&self, ctx: &AnalysisContext, spec: &SpecAliasData) -> Vec<MutationSpec>;
}

/// Options for code generation
#[derive(Debug, Clone, Default)]
pub struct GeneratorOptions {
    /// Generate accessor methods for relations
    pub generate_accessors: bool,
    /// Generate ID field for relations (e.g., order_id: OrderId)
    pub generate_id_fields: bool,
    /// Generate collection fields for relations (e.g., orders: Vec<Order>)
    pub generate_collection_fields: bool,
    /// Default derives to add
    pub default_derives: Vec<String>,
}

impl GeneratorOptions {
    pub fn new() -> Self {
        Self {
            generate_accessors: true,
            generate_id_fields: true,
            generate_collection_fields: false,
            default_derives: vec!["Debug".into(), "Clone".into()],
        }
    }

    pub fn with_accessors(mut self, enabled: bool) -> Self {
        self.generate_accessors = enabled;
        self
    }

    pub fn with_id_fields(mut self, enabled: bool) -> Self {
        self.generate_id_fields = enabled;
        self
    }

    pub fn with_collection_fields(mut self, enabled: bool) -> Self {
        self.generate_collection_fields = enabled;
        self
    }

    pub fn with_derives(mut self, derives: Vec<String>) -> Self {
        self.default_derives = derives;
        self
    }
}

/// Generator for domain model Specs
///
/// Generates struct fields and methods based on Spec relations.
///
/// # Generated Code
///
/// For `type UserSpec = Spec<DomainGroup, User, [DependsOn<Order>]>`:
///
/// - `AddField { field_name: "order_id", field_type: "OrderId" }`
/// - `AddMethod { method_name: "order_id", return_type: "&OrderId" }`
/// - `AddDerive { derives: ["Debug", "Clone"] }` (if not present)
pub struct DomainSpecGenerator {
    options: GeneratorOptions,
    /// Groups this generator applies to
    target_groups: Vec<String>,
}

impl DomainSpecGenerator {
    pub fn new() -> Self {
        Self {
            options: GeneratorOptions::new(),
            target_groups: vec!["DomainGroup".into()],
        }
    }

    pub fn with_options(mut self, options: GeneratorOptions) -> Self {
        self.options = options;
        self
    }

    pub fn with_groups(mut self, groups: Vec<String>) -> Self {
        self.target_groups = groups;
        self
    }

    /// Extract relation targets from a Spec (types it depends on)
    fn extract_relations(&self, ctx: &AnalysisContext, spec: &SpecAliasData) -> Vec<String> {
        use super::is_framework_type;

        let typeflow = ctx.typeflow_graph();
        let mut relations = Vec::new();

        let base_type = spec.wrapped_type_name.as_deref().unwrap_or("");

        for used_id in typeflow.types_used_by(spec.alias_id) {
            if let Some(path) = ctx.registry.path(used_id) {
                let kind = ctx.registry.kind(used_id);

                if !matches!(kind, Some(SymbolKind::Struct) | Some(SymbolKind::Enum)) {
                    continue;
                }

                let name = path.name();
                if is_framework_type(name) || name == base_type {
                    continue;
                }

                relations.push(name.to_string());
            }
        }

        relations
    }

    /// Check if struct has a field for the relation
    fn has_field_for(&self, ctx: &AnalysisContext, struct_id: SymbolId, target: &str) -> bool {
        let graph = ctx.code_graph();
        let target_lower = target.to_lowercase();

        for child_id in graph.children_of(struct_id) {
            if let Some(SymbolKind::Field) = ctx.registry.kind(child_id) {
                if let Some(path) = ctx.registry.path(child_id) {
                    if path.name().to_lowercase().contains(&target_lower) {
                        return true;
                    }
                }
            }
        }

        false
    }

    /// Check if struct has a method (simplified - checks children)
    fn has_method(&self, ctx: &AnalysisContext, struct_id: SymbolId, method_name: &str) -> bool {
        let graph = ctx.code_graph();

        // Check children (methods in impl blocks are children of the type)
        for child_id in graph.children_of(struct_id) {
            if let Some(SymbolKind::Method) = ctx.registry.kind(child_id) {
                if let Some(path) = ctx.registry.path(child_id) {
                    if path.name() == method_name {
                        return true;
                    }
                }
            }
        }

        false
    }

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

impl Default for DomainSpecGenerator {
    fn default() -> Self {
        Self::new()
    }
}

impl SpecGenerator for DomainSpecGenerator {
    fn name(&self) -> &'static str {
        "domain-spec-generator"
    }

    fn description(&self) -> &str {
        "Generates struct fields and methods from domain Spec relations"
    }

    fn matches(&self, spec: &SpecAliasData) -> bool {
        // Check if spec belongs to one of our target groups
        // We need to get the group name, but SpecAliasData only has group_idx
        // For now, match all specs with wrapped types
        spec.wrapped_type_id.is_some()
    }

    fn generate(&self, ctx: &AnalysisContext, spec: &SpecAliasData) -> Vec<MutationSpec> {
        let mut mutations = Vec::new();

        // Get the wrapped struct
        let struct_id = match spec.wrapped_type_id {
            Some(id) => id,
            None => return mutations,
        };

        let _struct_name = match &spec.wrapped_type_name {
            Some(name) => name.clone(),
            None => return mutations,
        };

        // Extract relations
        let relations = self.extract_relations(ctx, spec);

        // Generate fields for each relation
        for relation in &relations {
            let field_name = format!("{}_id", self.to_snake_case(relation));
            let field_type = format!("{}Id", relation);

            // Check if field already exists
            if !self.has_field_for(ctx, struct_id, relation) && self.options.generate_id_fields {
                mutations.push(MutationSpec::AddField {
                    target: ryo_executor::MutationTargetSymbol::ById(struct_id),
                    field_name: field_name.clone(),
                    field_type: field_type.clone(),
                    visibility: Visibility::Pub,
                });
            }

            // Generate accessor method
            if self.options.generate_accessors && !self.has_method(ctx, struct_id, &field_name) {
                mutations.push(MutationSpec::AddMethod {
                    target: ryo_executor::MutationTargetSymbol::ById(struct_id),
                    method_name: field_name.clone(),
                    params: vec![],
                    return_type: Some(format!("&{}", field_type)),
                    body: format!("&self.{}", field_name),
                    is_pub: true,
                    self_param: Some(SelfParam::Ref),
                });
            }
        }

        // Add default derives if configured
        if !self.options.default_derives.is_empty() {
            // Check which derives are missing (simplified - always add for now)
            mutations.push(MutationSpec::AddDerive {
                target: ryo_executor::MutationTargetSymbol::ById(struct_id),
                derives: self.options.default_derives.clone(),
            });
        }

        mutations
    }
}

/// Registry for SpecGenerators
#[derive(Default)]
pub struct SpecGeneratorRegistry {
    generators: Vec<Box<dyn SpecGenerator>>,
}

impl SpecGeneratorRegistry {
    pub fn new() -> Self {
        Self::default()
    }

    /// Register a generator
    pub fn register<G: SpecGenerator + 'static>(&mut self, generator: G) {
        self.generators.push(Box::new(generator));
    }

    /// Generate MutationSpecs for a Spec using all matching generators
    pub fn generate_for(&self, ctx: &AnalysisContext, spec: &SpecAliasData) -> Vec<MutationSpec> {
        let mut all_mutations = Vec::new();

        for generator in &self.generators {
            if generator.matches(spec) {
                let mutations = generator.generate(ctx, spec);
                all_mutations.extend(mutations);
            }
        }

        all_mutations
    }

    /// Generate MutationSpecs for all Specs in the context
    ///
    /// Iterates all TypeAliases matching Spec pattern and generates code.
    pub fn generate_all(&self, ctx: &AnalysisContext) -> Vec<(String, Vec<MutationSpec>)> {
        let mut results = Vec::new();

        // Find all TypeAliases that look like Specs
        for symbol_id in ctx.registry.iter_by_kind(SymbolKind::TypeAlias) {
            let path = match ctx.registry.path(symbol_id) {
                Some(p) => p,
                None => continue,
            };

            let alias_name = path.name();
            if !alias_name.ends_with("Spec") || alias_name == "Spec" {
                continue;
            }

            // Build SpecAliasData manually
            let base_type = &alias_name[..alias_name.len() - 4]; // Remove "Spec"
            let wrapped_type_id = self.find_struct_by_name(ctx, base_type);

            let spec_data = SpecAliasData {
                alias_id: symbol_id,
                alias_name: alias_name.to_string(),
                wrapped_type_id,
                wrapped_type_name: Some(base_type.to_string()),
                group_idx: 0, // Unknown
                source: ryo_analysis::query::SpecSource::TypeAlias,
            };

            let mutations = self.generate_for(ctx, &spec_data);
            if !mutations.is_empty() {
                results.push((alias_name.to_string(), mutations));
            }
        }

        results
    }

    /// Find struct by name
    fn find_struct_by_name(&self, ctx: &AnalysisContext, name: &str) -> Option<SymbolId> {
        for symbol_id in ctx.registry.iter_by_kind(SymbolKind::Struct) {
            if let Some(path) = ctx.registry.path(symbol_id) {
                if path.name() == name {
                    return Some(symbol_id);
                }
            }
        }
        None
    }
}

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

    #[test]
    fn test_to_snake_case() {
        let gen = DomainSpecGenerator::new();
        assert_eq!(gen.to_snake_case("Order"), "order");
        assert_eq!(gen.to_snake_case("OrderItem"), "order_item");
        assert_eq!(gen.to_snake_case("HTTPRequest"), "h_t_t_p_request");
    }

    #[test]
    fn test_generator_options() {
        let opts = GeneratorOptions::new()
            .with_accessors(false)
            .with_id_fields(true)
            .with_derives(vec!["Serialize".into()]);

        assert!(!opts.generate_accessors);
        assert!(opts.generate_id_fields);
        assert_eq!(opts.default_derives, vec!["Serialize"]);
    }

    #[test]
    fn test_domain_spec_generator_new() {
        let gen = DomainSpecGenerator::new();
        assert_eq!(gen.name(), "domain-spec-generator");
        assert!(gen.options.generate_accessors);
        assert!(gen.options.generate_id_fields);
    }
}