//! TDD Test for run_mcp_server refactoring (Sprint 79)
//!
//! Following Toyota Way TDD principles:
//! 1. Write test FIRST (Red)
//! 2. Make it pass (Green)
//! 3. Refactor to reduce cognitive complexity from 49 to ≤10 (Refactor)
//!
//! Current: Cognitive complexity 49, Cyclomatic complexity 11
//! Target: Cognitive complexity ≤10, maintain functionality

use anyhow::Result;
use pmat::models::template::{TemplateCategory, Toolchain};
use pmat::{
    models::template::TemplateResource, ContentCache, MetadataCache,
    PublicTemplateRenderer as TemplateRenderer, S3Client, TemplateServerTrait,
};
use std::sync::Arc;

// Mock template server for testing
struct MockTemplateServer {
    renderer: TemplateRenderer,
}

#[async_trait::async_trait]
impl TemplateServerTrait for MockTemplateServer {
    async fn get_template_metadata(&self, _uri: &str) -> Result<Arc<TemplateResource>> {
        let resource = TemplateResource {
            uri: "mock://template".to_string(),
            name: "Mock Template".to_string(),
            description: "Mock template for testing".to_string(),
            toolchain: Toolchain::RustCli {
                cargo_features: vec![],
            },
            category: TemplateCategory::Context,
            parameters: vec![],
            s3_object_key: "mock-key".to_string(),
            content_hash: "abc123".to_string(),
            semantic_version: semver::Version::new(1, 0, 0),
            dependency_graph: vec![],
        };
        Ok(Arc::new(resource))
    }

    async fn get_template_content(&self, _s3_key: &str) -> Result<Arc<str>> {
        Ok(Arc::from("Mock template content"))
    }

    async fn list_templates(&self, _prefix: &str) -> Result<Vec<Arc<TemplateResource>>> {
        Ok(vec![])
    }

    fn get_renderer(&self) -> &TemplateRenderer {
        &self.renderer
    }

    fn get_metadata_cache(&self) -> Option<&MetadataCache> {
        None
    }

    fn get_content_cache(&self) -> Option<&ContentCache> {
        None
    }

    fn get_s3_client(&self) -> Option<&S3Client> {
        None
    }

    fn get_bucket_name(&self) -> Option<&str> {
        None
    }
}

/// Test MCP server basic structure and initialization
#[tokio::test]
async fn test_run_mcp_server_structure() {
    // Test that run_mcp_server can be called with mock server
    // Note: This test focuses on the refactoring structure, not full I/O testing

    // Create a real renderer for testing
    let renderer = TemplateRenderer::new().expect("Failed to create renderer");
    let mock_server = Arc::new(MockTemplateServer { renderer });

    // Verify the mock server implements the trait correctly
    let _metadata_future = mock_server.get_template_metadata("test");
    let _content_future = mock_server.get_template_content("test");
    let _list_future = mock_server.list_templates("test");

    // Verify accessors work
    assert!(!std::ptr::addr_of!(*mock_server.get_renderer()).is_null());
    assert!(mock_server.get_metadata_cache().is_none());
    assert!(mock_server.get_content_cache().is_none());
    assert!(mock_server.get_s3_client().is_none());
    assert!(mock_server.get_bucket_name().is_none());
}

/// Test error handling patterns that will be preserved during refactoring
#[test]
fn test_run_mcp_server_error_patterns() {
    // Test JSON parsing error handling
    let invalid_json = "{ invalid json }";
    let parse_result = serde_json::from_str::<serde_json::Value>(invalid_json);
    assert!(parse_result.is_err());

    // Test response serialization
    let response = serde_json::json!({
        "jsonrpc": "2.0",
        "id": null,
        "error": {
            "code": -32700,
            "message": "Parse error"
        }
    });
    let serialized = serde_json::to_string(&response);
    assert!(serialized.is_ok());
}

/// Test the MCP request/response cycle structure
#[test]
fn test_mcp_request_response_structure() {
    // Test basic MCP request structure
    let request_json = r#"{
        "jsonrpc": "2.0",
        "method": "test",
        "id": 1,
        "params": {}
    }"#;

    let parse_result = serde_json::from_str::<serde_json::Value>(request_json);
    assert!(parse_result.is_ok());

    let parsed = parse_result.unwrap();
    assert_eq!(parsed["method"], "test");
    assert_eq!(parsed["id"], 1);
}
