//! Service structure macro implementation
//!
//! Generates complete service architectures with:
//! - Service trait definitions
//! - Business logic structure
//! - Error handling patterns
//! - Integration patterns
//! - GraphQL resolver generation

use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};

use crate::utils::*;

/// Implementation of the Service derive macro
pub fn derive_service(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let struct_name = &input.ident;
    let struct_name_str = struct_name.to_string();
    
    // Extract service attributes
    let service_name = get_attribute_value(&input.attrs, "service", "name")
        .unwrap_or_else(|| struct_name_str.to_lowercase());
    let features = get_service_features(&input.attrs);
    
    // Generate service trait
    let service_trait = generate_service_trait(struct_name, &features);
    
    // Generate service implementation
    let service_impl = generate_service_implementation(struct_name, &features);
    
    // Generate GraphQL resolvers if enabled
    let graphql_resolvers = if features.contains(&"graphql".to_string()) {
        generate_graphql_resolvers(struct_name)
    } else {
        quote! {}
    };
    
    // Generate error types
    let error_types = generate_service_error_types(struct_name);
    
    // Generate config types
    let config_types = generate_service_config_types(struct_name, &service_name);
    
    let expanded = quote! {
        #error_types
        #config_types
        #service_trait
        #service_impl
        #graphql_resolvers
    };
    
    TokenStream::from(expanded)
}

/// Extract service features from attributes
fn get_service_features(attrs: &[syn::Attribute]) -> Vec<String> {
    let mut features = Vec::new();
    
    for attr in attrs {
        if attr.path().is_ident("service") {
            let _ = attr.parse_nested_meta(|meta| {
                if meta.path.is_ident("features") {
                    if let Ok(lit_str) = meta.value()?.parse::<syn::LitStr>() {
                        let feature_string = lit_str.value();
                        let feature_list: Vec<&str> = feature_string.split(',').collect();
                        for feature in feature_list {
                            features.push(feature.trim().to_string());
                        }
                    }
                }
                Ok(())
            });
        }
    }
    
    features
}

/// Generate service trait definition
fn generate_service_trait(struct_name: &syn::Ident, features: &[String]) -> TokenStream2 {
    let trait_name = syn::Ident::new(&format!("{}ServiceTrait", struct_name), proc_macro2::Span::call_site());
    let result_type = syn::Ident::new(&format!("{}Result", struct_name), proc_macro2::Span::call_site());
    
    // Generate basic CRUD methods
    let crud_methods = generate_crud_methods(struct_name, &result_type);
    
    // Generate feature-specific methods
    let feature_methods = generate_feature_methods(features, &result_type);
    
    quote! {
        /// Service trait for #struct_name
        #[async_trait::async_trait]
        pub trait #trait_name: Send + Sync {
            #crud_methods
            #feature_methods
        }
    }
}

/// Generate CRUD methods for service trait
fn generate_crud_methods(struct_name: &syn::Ident, result_type: &syn::Ident) -> TokenStream2 {
    let entity_name = struct_name.to_string().replace("Service", "");
    let entity_ident = syn::Ident::new(&entity_name, proc_macro2::Span::call_site());
    let create_input = syn::Ident::new(&format!("Create{}Input", entity_name), proc_macro2::Span::call_site());
    let update_input = syn::Ident::new(&format!("Update{}Input", entity_name), proc_macro2::Span::call_site());
    
    quote! {
        /// Create a new entity
        async fn create(&self, product: &str, input: #create_input) -> #result_type<#entity_ident>;
        
        /// Get entity by ID
        async fn get_by_id(&self, id: uuid::Uuid, product: &str) -> #result_type<Option<#entity_ident>>;
        
        /// Update an existing entity
        async fn update(&self, id: uuid::Uuid, product: &str, input: #update_input) -> #result_type<#entity_ident>;
        
        /// Delete an entity
        async fn delete(&self, id: uuid::Uuid, product: &str) -> #result_type<bool>;
        
        /// List entities with pagination
        async fn list(&self, product: &str, limit: i64, offset: i64) -> #result_type<Vec<#entity_ident>>;
        
        /// Count total entities for product
        async fn count(&self, product: &str) -> #result_type<i64>;
        
        /// Check if entity exists
        async fn exists(&self, id: uuid::Uuid, product: &str) -> #result_type<bool>;
    }
}

/// Generate feature-specific methods
fn generate_feature_methods(features: &[String], result_type: &syn::Ident) -> TokenStream2 {
    let mut methods = Vec::new();
    
    if features.contains(&"brazilian".to_string()) {
        methods.push(quote! {
            /// Validate Brazilian CPF
            async fn validate_cpf(&self, cpf: &str) -> #result_type<bool>;
            
            /// Validate Brazilian CEP
            async fn validate_cep(&self, cep: &str) -> #result_type<bool>;
        });
    }
    
    if features.contains(&"payments".to_string()) {
        methods.push(quote! {
            /// Process payment for entity
            async fn process_payment(&self, entity_id: uuid::Uuid, payment_method: PaymentMethod) -> #result_type<PaymentResult>;
            
            /// Generate PIX payment
            async fn generate_pix_payment(&self, entity_id: uuid::Uuid) -> #result_type<PixPaymentData>;
            
            /// Generate Boleto payment  
            async fn generate_boleto_payment(&self, entity_id: uuid::Uuid) -> #result_type<BoletoPaymentData>;
        });
    }
    
    if features.contains(&"notifications".to_string()) {
        methods.push(quote! {
            /// Send notification for entity
            async fn send_notification(&self, entity_id: uuid::Uuid, notification_type: NotificationType) -> #result_type<()>;
        });
    }
    
    quote! {
        #(#methods)*
    }
}

/// Generate service implementation structure
fn generate_service_implementation(struct_name: &syn::Ident, features: &[String]) -> TokenStream2 {
    let trait_name = syn::Ident::new(&format!("{}ServiceTrait", struct_name), proc_macro2::Span::call_site());
    let result_type = syn::Ident::new(&format!("{}Result", struct_name), proc_macro2::Span::call_site());
    let error_type = syn::Ident::new(&format!("{}Error", struct_name), proc_macro2::Span::call_site());
    let config_type = syn::Ident::new(&format!("{}Config", struct_name), proc_macro2::Span::call_site());
    
    let entity_name = struct_name.to_string().replace("Service", "");
    let entity_ident = syn::Ident::new(&entity_name, proc_macro2::Span::call_site());
    let repository_trait = syn::Ident::new(&format!("{}RepositoryTrait", entity_name), proc_macro2::Span::call_site());
    let create_input = syn::Ident::new(&format!("Create{}Input", entity_name), proc_macro2::Span::call_site());
    let update_input = syn::Ident::new(&format!("Update{}Input", entity_name), proc_macro2::Span::call_site());
    
    // Generate dependency fields based on features
    let dependency_fields = generate_dependency_fields(features);
    let constructor_params = generate_constructor_params(features);
    let constructor_assigns = generate_constructor_assigns(features);
    
    quote! {
        /// Service implementation for #struct_name
        pub struct #struct_name {
            repository: std::sync::Arc<dyn #repository_trait>,
            config: #config_type,
            #dependency_fields
        }
        
        impl #struct_name {
            /// Create a new service instance
            pub fn new(
                repository: std::sync::Arc<dyn #repository_trait>,
                config: #config_type,
                #constructor_params
            ) -> Self {
                Self {
                    repository,
                    config,
                    #constructor_assigns
                }
            }
        }
        
        #[async_trait::async_trait]
        impl #trait_name for #struct_name {
            async fn create(&self, product: &str, input: #create_input) -> #result_type<#entity_ident> {
                // Validate input
                input.validate().map_err(#error_type::Validation)?;
                
                // Create entity
                let entity = #entity_ident::new(product.to_string(), /* fields from input */);
                
                // Save via repository
                let saved_entity = self.repository.create(&entity).await?;
                
                Ok(saved_entity)
            }
            
            async fn get_by_id(&self, id: uuid::Uuid, product: &str) -> #result_type<Option<#entity_ident>> {
                self.repository.find_by_id(id, product).await
            }
            
            async fn update(&self, id: uuid::Uuid, product: &str, input: #update_input) -> #result_type<#entity_ident> {
                // Get existing entity
                let mut entity = self.repository.find_by_id(id, product)
                    .await?
                    .ok_or_else(|| #error_type::NotFound(format!("Entity not found: {}", id)))?;
                
                // Apply updates
                // entity.update_from_input(input);
                
                // Save changes
                let updated_entity = self.repository.update(&entity).await?;
                
                Ok(updated_entity)
            }
            
            async fn delete(&self, id: uuid::Uuid, product: &str) -> #result_type<bool> {
                self.repository.delete(id, product).await
            }
            
            async fn list(&self, product: &str, limit: i64, offset: i64) -> #result_type<Vec<#entity_ident>> {
                self.repository.list_by_product(product, limit, offset).await
            }
            
            async fn count(&self, product: &str) -> #result_type<i64> {
                self.repository.count_by_product(product).await
            }
            
            async fn exists(&self, id: uuid::Uuid, product: &str) -> #result_type<bool> {
                self.repository.exists(id, product).await
            }
        }
    }
}

/// Generate dependency fields based on features
fn generate_dependency_fields(features: &[String]) -> TokenStream2 {
    let mut fields = Vec::new();
    
    if features.contains(&"cache".to_string()) {
        fields.push(quote! { cache: std::sync::Arc<dyn CacheServiceTrait>, });
    }
    
    if features.contains(&"payments".to_string()) {
        fields.push(quote! { payment_service: std::sync::Arc<dyn PaymentServiceTrait>, });
    }
    
    if features.contains(&"notifications".to_string()) {
        fields.push(quote! { notification_service: std::sync::Arc<dyn NotificationServiceTrait>, });
    }
    
    quote! { #(#fields)* }
}

/// Generate constructor parameters based on features
fn generate_constructor_params(features: &[String]) -> TokenStream2 {
    let mut params = Vec::new();
    
    if features.contains(&"cache".to_string()) {
        params.push(quote! { cache: std::sync::Arc<dyn CacheServiceTrait>, });
    }
    
    if features.contains(&"payments".to_string()) {
        params.push(quote! { payment_service: std::sync::Arc<dyn PaymentServiceTrait>, });
    }
    
    if features.contains(&"notifications".to_string()) {
        params.push(quote! { notification_service: std::sync::Arc<dyn NotificationServiceTrait>, });
    }
    
    quote! { #(#params)* }
}

/// Generate constructor assignments based on features
fn generate_constructor_assigns(features: &[String]) -> TokenStream2 {
    let mut assigns = Vec::new();
    
    if features.contains(&"cache".to_string()) {
        assigns.push(quote! { cache, });
    }
    
    if features.contains(&"payments".to_string()) {
        assigns.push(quote! { payment_service, });
    }
    
    if features.contains(&"notifications".to_string()) {
        assigns.push(quote! { notification_service, });
    }
    
    quote! { #(#assigns)* }
}

/// Generate GraphQL resolvers
fn generate_graphql_resolvers(struct_name: &syn::Ident) -> TokenStream2 {
    let entity_name = struct_name.to_string().replace("Service", "");
    let query_name = syn::Ident::new(&format!("{}Query", entity_name), proc_macro2::Span::call_site());
    let mutation_name = syn::Ident::new(&format!("{}Mutation", entity_name), proc_macro2::Span::call_site());
    let service_trait = syn::Ident::new(&format!("{}ServiceTrait", struct_name), proc_macro2::Span::call_site());
    
    quote! {
        /// GraphQL Query resolvers
        pub struct #query_name;
        
        #[async_graphql::Object]
        impl #query_name {
            /// Get entity by ID
            async fn get_by_id(
                &self,
                ctx: &async_graphql::Context<'_>,
                id: uuid::Uuid,
            ) -> async_graphql::Result<Option<crate::models::#entity_name>> {
                let service = ctx.data::<std::sync::Arc<dyn #service_trait>>()?;
                let product = ctx.data::<String>()?; // Product from context
                
                let result = service.get_by_id(id, product).await?;
                Ok(result)
            }
            
            /// List entities with pagination
            async fn list(
                &self,
                ctx: &async_graphql::Context<'_>,
                limit: Option<i32>,
                offset: Option<i32>,
            ) -> async_graphql::Result<Vec<crate::models::#entity_name>> {
                let service = ctx.data::<std::sync::Arc<dyn #service_trait>>()?;
                let product = ctx.data::<String>()?;
                
                let limit = limit.unwrap_or(50) as i64;
                let offset = offset.unwrap_or(0) as i64;
                
                let result = service.list(product, limit, offset).await?;
                Ok(result)
            }
        }
        
        /// GraphQL Mutation resolvers
        pub struct #mutation_name;
        
        #[async_graphql::Object]
        impl #mutation_name {
            /// Create new entity
            async fn create(
                &self,
                ctx: &async_graphql::Context<'_>,
                input: crate::api::CreateInput,
            ) -> async_graphql::Result<crate::models::Entity> {
                let service = ctx.data::<std::sync::Arc<dyn #service_trait>>()?;
                let product = ctx.data::<String>()?;
                
                let result = service.create(product, input.into()).await?;
                Ok(result)
            }
            
            /// Update existing entity
            async fn update(
                &self,
                ctx: &async_graphql::Context<'_>,
                id: uuid::Uuid,
                input: crate::api::UpdateInput,
            ) -> async_graphql::Result<crate::models::Entity> {
                let service = ctx.data::<std::sync::Arc<dyn #service_trait>>()?;
                let product = ctx.data::<String>()?;
                
                let result = service.update(id, product, input.into()).await?;
                Ok(result)
            }
            
            /// Delete entity
            async fn delete(
                &self,
                ctx: &async_graphql::Context<'_>,
                id: uuid::Uuid,
            ) -> async_graphql::Result<bool> {
                let service = ctx.data::<std::sync::Arc<dyn #service_trait>>()?;
                let product = ctx.data::<String>()?;
                
                let result = service.delete(id, product).await?;
                Ok(result)
            }
        }
    }
}

/// Generate error types
fn generate_service_error_types(struct_name: &syn::Ident) -> TokenStream2 {
    let error_name = syn::Ident::new(&format!("{}Error", struct_name), proc_macro2::Span::call_site());
    let result_name = syn::Ident::new(&format!("{}Result", struct_name), proc_macro2::Span::call_site());
    
    quote! {
        /// Error types for #struct_name
        #[derive(Debug, thiserror::Error)]
        pub enum #error_name {
            #[error("Not found: {0}")]
            NotFound(String),
            
            #[error("Validation error: {0}")]
            Validation(String),
            
            #[error("Database error: {0}")]
            Database(#[from] sqlx::Error),
            
            #[error("Cache error: {0}")]
            Cache(String),
            
            #[error("Internal error: {0}")]
            Internal(String),
        }
        
        /// Result type alias for #struct_name operations
        pub type #result_name<T> = Result<T, #error_name>;
    }
}

/// Generate config types
fn generate_service_config_types(struct_name: &syn::Ident, service_name: &str) -> TokenStream2 {
    let config_name = syn::Ident::new(&format!("{}Config", struct_name), proc_macro2::Span::call_site());
    
    quote! {
        /// Configuration for #struct_name
        #[derive(Debug, Clone, serde::Deserialize)]
        pub struct #config_name {
            /// Service name
            pub service_name: String,
            
            /// Database configuration
            pub database: DatabaseConfig,
            
            /// Cache configuration
            pub cache: CacheConfig,
            
            /// Feature flags
            pub features: std::collections::HashMap<String, bool>,
        }
        
        impl Default for #config_name {
            fn default() -> Self {
                Self {
                    service_name: #service_name.to_string(),
                    database: DatabaseConfig::default(),
                    cache: CacheConfig::default(),
                    features: std::collections::HashMap::new(),
                }
            }
        }
        
        impl #config_name {
            /// Load configuration from environment
            pub fn from_env() -> Result<Self, Box<dyn std::error::Error>> {
                // Implementation would read from environment variables
                Ok(Self::default())
            }
            
            /// Check if feature is enabled
            pub fn is_feature_enabled(&self, feature: &str) -> bool {
                self.features.get(feature).copied().unwrap_or(false)
            }
        }
    }
}