use crate::agent::{SystemPrompt, SystemPromptContext, SystemPromptProvider};
use crate::command::context::CommandContext;
use crate::command::handler::CommandHandler;
use crate::command::response::{CommandError, CommandResponse, MessageKind};
use crate::command::Command;
use crate::config::LLMProviderConfig;
use crate::gateway::agent_prompt_provider::SimpleAgentPromptProvider;
use crate::storage::{SessionRecord, SessionStore};
use async_trait::async_trait;
use chrono::{Local, TimeZone};
use std::path::PathBuf;
use std::sync::Arc;

/// 保存会话命令处理器
///
/// 将当前会话内容（系统提示词和消息历史）保存到 Markdown 文件
pub struct SaveSessionCommandHandler {
    store: Arc<SessionStore>,
    provider_config: LLMProviderConfig,
}

impl SaveSessionCommandHandler {
    /// 创建新的保存会话命令处理器
    ///
    /// # Arguments
    /// * `store` - 会话存储
    /// * `provider_config` - LLM 提供者配置（用于构建系统提示词）
    pub fn new(store: Arc<SessionStore>, provider_config: LLMProviderConfig) -> Self {
        Self {
            store,
            provider_config,
        }
    }

    /// 从会话记录获取存储（用于测试）
    #[cfg(test)]
    fn store(&self) -> &Arc<SessionStore> {
        &self.store
    }
}

#[async_trait]
impl CommandHandler for SaveSessionCommandHandler {
    fn can_handle(&self, cmd: &Command) -> bool {
        matches!(cmd, Command::SaveSession { .. })
    }

    async fn handle(
        &self,
        cmd: Command,
        ctx: CommandContext,
    ) -> Result<CommandResponse, CommandError> {
        match cmd {
            Command::SaveSession { filepath } => {
                handle_save_session(self, filepath, ctx).await
            }
            _ => unreachable!(),
        }
    }
}

/// 处理保存会话命令
async fn handle_save_session(
    handler: &SaveSessionCommandHandler,
    filepath: Option<String>,
    ctx: CommandContext,
) -> Result<CommandResponse, CommandError> {
    let session_id = ctx
        .session_id
        .as_deref()
        .ok_or_else(|| CommandError::new("NO_SESSION", "No active session".to_string()))?;

    // 获取会话记录
    let record = handler
        .store
        .get_session(session_id)
        .map_err(|e| CommandError::new("SESSION_ERROR", e.to_string()))?
        .ok_or_else(|| CommandError::new("SESSION_NOT_FOUND", "Session not found".to_string()))?;

    // 获取所有消息（包括历史）
    let messages = handler
        .store
        .load_all_messages(session_id)
        .map_err(|e| CommandError::new("LOAD_MESSAGES_ERROR", e.to_string()))?;

    // 计算用户消息数（用于系统提示词构建）
    let user_message_count = messages.iter().filter(|m| m.role == "user").count();

    // 构建系统提示词
    let system_prompt = build_system_prompt(&handler.provider_config, &record, user_message_count);

    // 生成 Markdown 内容
    let markdown = generate_markdown(&record, &system_prompt, &messages);

    // 确定输出路径
    let output_path = resolve_filepath(filepath, &record);

    // 创建父目录
    if let Some(parent) = output_path.parent() {
        if !parent.as_os_str().is_empty() && !parent.exists() {
            std::fs::create_dir_all(parent).map_err(|e| {
                CommandError::new(
                    "CREATE_DIR_ERROR",
                    format!("Failed to create directory: {}", e),
                )
            })?;
        }
    }

    // 写入文件
    std::fs::write(&output_path, markdown).map_err(|e| {
        CommandError::new(
            "WRITE_FILE_ERROR",
            format!("Failed to write file: {}", e),
        )
    })?;

    Ok(CommandResponse::success(ctx.request_id)
        .with_message(
            MessageKind::Notification,
            &format!("Session saved to: {}", output_path.display()),
        )
        .with_metadata("filepath", output_path.to_string_lossy().as_ref())
        .with_metadata("message_count", &messages.len().to_string()))
}

/// 构建系统提示词
fn build_system_prompt(
    provider_config: &LLMProviderConfig,
    record: &SessionRecord,
    user_message_count: usize,
) -> Option<SystemPrompt> {
    let provider = SimpleAgentPromptProvider::new(provider_config.clone());
    let context = SystemPromptContext {
        session_id: Some(record.id.clone()),
        chat_id: record.chat_id.clone(),
        user_message_count,
    };
    provider.build(&context)
}

/// 生成 Markdown 内容
fn generate_markdown(
    record: &SessionRecord,
    system_prompt: &Option<SystemPrompt>,
    messages: &[crate::bus::ChatMessage],
) -> String {
    let mut output = String::new();

    // YAML frontmatter
    output.push_str("---\n");
    output.push_str(&format!("title: {}\n", escape_yaml_string(&record.title)));
    output.push_str(&format!("session_id: {}\n", record.id));
    output.push_str(&format!("channel: {}\n", record.channel_name));
    output.push_str(&format!("chat_id: {}\n", record.chat_id));
    output.push_str(&format!(
        "created_at: {}\n",
        format_timestamp(record.created_at)
    ));
    output.push_str(&format!(
        "updated_at: {}\n",
        format_timestamp(record.updated_at)
    ));
    output.push_str(&format!(
        "last_active_at: {}\n",
        format_timestamp(record.last_active_at)
    ));
    output.push_str(&format!("message_count: {}\n", messages.len()));
    output.push_str("---\n\n");

    // 系统提示词
    output.push_str("# System Prompt\n\n");
    if let Some(prompt) = system_prompt {
        output.push_str("```\n");
        output.push_str(&prompt.content);
        output.push_str("\n```\n\n");
    } else {
        output.push_str("*No system prompt available*\n\n");
    }

    // 消息历史
    output.push_str("# Message History\n\n");

    for (idx, msg) in messages.iter().enumerate() {
        output.push_str(&format!("## Message {}\n\n", idx + 1));
        output.push_str(&format!("**Role:** {}\n\n", msg.role));
        output.push_str(&format!("**ID:** {}\n\n", msg.id));
        output.push_str(&format!(
            "**Time:** {}\n\n",
            format_timestamp(msg.timestamp)
        ));

        if let Some(ref ctx) = msg.system_context {
            output.push_str(&format!("**System Context:** `{}`\n\n", ctx));
        }

        if let Some(ref tool_name) = msg.tool_name {
            output.push_str(&format!("**Tool Name:** `{}`\n\n", tool_name));
        }

        if let Some(ref tool_call_id) = msg.tool_call_id {
            output.push_str(&format!("**Tool Call ID:** `{}`\n\n", tool_call_id));
        }

        if let Some(ref reasoning) = msg.reasoning_content {
            output.push_str("### Reasoning\n\n");
            output.push_str("```\n");
            output.push_str(reasoning);
            output.push_str("\n```\n\n");
        }

        // Content
        output.push_str("### Content\n\n");
        if msg.content.is_empty() {
            output.push_str("*empty*\n\n");
        } else {
            output.push_str(&format!("{}\n\n", format_message_content(&msg.content)));
        }

        // Tool calls
        if let Some(ref calls) = msg.tool_calls {
            if !calls.is_empty() {
                output.push_str("### Tool Calls\n\n");
                for call in calls {
                    output.push_str(&format!("- **{}** (`{}`)\n", call.name, call.id));
                    output.push_str("  ```json\n");
                    let args_json = serde_json::to_string_pretty(&call.arguments)
                        .unwrap_or_else(|_| call.arguments.to_string());
                    for line in args_json.lines() {
                        output.push_str(&format!("  {}\n", line));
                    }
                    output.push_str("  ```\n");
                }
                output.push('\n');
            }
        }

        // Media refs
        if !msg.media_refs.is_empty() {
            output.push_str("### Media References\n\n");
            for media_ref in &msg.media_refs {
                output.push_str(&format!("- `{}`\n", media_ref));
            }
            output.push('\n');
        }

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

    output
}

/// 格式化消息内容
///
/// 如果内容包含特殊字符，使用代码块包装
fn format_message_content(content: &str) -> String {
    // 如果内容包含代码块标记或表格标记，使用原始格式
    if content.contains("```") || content.contains("| ") {
        format!("```\n{}\n```", content)
    } else {
        content.to_string()
    }
}

/// 转义 YAML 字符串
fn escape_yaml_string(s: &str) -> String {
    if s.contains('\n') || s.contains('"') || s.contains(':') || s.starts_with(' ') {
        // 使用双引号包裹并转义内部的双引号
        format!("\"{}\"", s.replace('"', "\\\""))
    } else {
        s.to_string()
    }
}

/// 格式化时间戳
fn format_timestamp(ts: i64) -> String {
    Local
        .timestamp_millis_opt(ts)
        .single()
        .map(|dt| dt.format("%Y-%m-%d %H:%M:%S").to_string())
        .unwrap_or_else(|| format!("{}", ts))
}

/// 解析文件路径
///
/// 如果未提供路径，自动生成基于会话标题和时间戳的文件名
fn resolve_filepath(filepath: Option<String>, record: &SessionRecord) -> PathBuf {
    match filepath {
        Some(path) => PathBuf::from(path),
        None => {
            // 生成安全标题（替换特殊字符）
            let safe_title = record
                .title
                .replace(' ', "_")
                .replace('/', "_")
                .replace('\\', "_")
                .replace(':', "_")
                .replace('<', "_")
                .replace('>', "_")
                .replace('|', "_")
                .replace('?', "_")
                .replace('*', "_")
                .replace('"', "_");

            // 使用标题或 session_id 作为文件名
            let base_name = if safe_title.is_empty() {
                format!("session_{}", &record.id[..8.min(record.id.len())])
            } else {
                safe_title
            };

            // 添加时间戳
            let timestamp = Local::now().format("%Y%m%d_%H%M%S");
            let filename = format!("{}_{}.md", base_name, timestamp);

            PathBuf::from(filename)
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::storage::{SessionRecord, SessionStore};
    use std::collections::HashMap;

    fn test_config() -> LLMProviderConfig {
        LLMProviderConfig {
            provider_type: "openai".to_string(),
            name: "test".to_string(),
            base_url: "http://localhost".to_string(),
            api_key: "test-key".to_string(),
            extra_headers: HashMap::new(),
            llm_timeout_secs: 120,
            memory_maintenance_timeout_secs: 600,
            model_id: "test-model".to_string(),
            temperature: Some(0.0),
            max_tokens: Some(32),
            context_window_tokens: None,
            tool_result_max_chars: 20_000,
            context_tool_result_trim_chars: 20_000,
            model_extra: HashMap::new(),
            max_tool_iterations: 1,
        }
    }

    fn create_test_record(id: &str, title: &str) -> SessionRecord {
        SessionRecord {
            id: id.to_string(),
            title: title.to_string(),
            channel_name: "cli".to_string(),
            chat_id: id.to_string(),
            summary: None,
            created_at: 1705312800000, // 2024-01-15 10:00:00
            updated_at: 1705316400000, // 2024-01-15 11:00:00
            last_active_at: 1705316400000,
            archived_at: None,
            deleted_at: None,
            message_count: 0,
            reset_cutoff_seq: 0,
            user_turn_count: 0,
            agent_prompt_reinjection_count: 0,
        }
    }

    #[test]
    fn test_resolve_filepath_with_custom_path() {
        let record = create_test_record("test-123", "My Session");
        let path = resolve_filepath(Some("/custom/path/file.md".to_string()), &record);
        assert_eq!(path, PathBuf::from("/custom/path/file.md"));
    }

    #[test]
    fn test_resolve_filepath_generates_filename_with_title() {
        let record = create_test_record("test-123", "My Session");
        let path = resolve_filepath(None, &record);
        let filename = path.file_name().unwrap().to_str().unwrap();

        assert!(filename.starts_with("My_Session_"));
        assert!(filename.ends_with(".md"));
    }

    #[test]
    fn test_resolve_filepath_generates_filename_with_id_when_title_empty() {
        let record = create_test_record("abc12345-xyz", "");
        let path = resolve_filepath(None, &record);
        let filename = path.file_name().unwrap().to_str().unwrap();

        assert!(filename.starts_with("session_abc123"));
        assert!(filename.ends_with(".md"));
    }

    #[test]
    fn test_escape_yaml_string() {
        assert_eq!(escape_yaml_string("simple"), "simple");
        assert_eq!(escape_yaml_string("with: colon"), "\"with: colon\"");
        assert_eq!(escape_yaml_string("with \"quote\""), "\"with \\\"quote\\\"\"");
    }

    #[test]
    fn test_format_message_content() {
        assert_eq!(format_message_content("hello"), "hello");
        assert_eq!(
            format_message_content("```code```"),
            "```\n```code```\n```"
        );
    }

    #[test]
    fn test_generate_markdown_structure() {
        let record = create_test_record("test-123", "Test Session");
        let messages = vec![crate::bus::ChatMessage::system("System prompt here")];

        let markdown = generate_markdown(&record, &None, &messages);

        assert!(markdown.contains("---"));
        assert!(markdown.contains("title:"));
        assert!(markdown.contains("session_id: test-123"));
        assert!(markdown.contains("# System Prompt"));
        assert!(markdown.contains("# Message History"));
        assert!(markdown.contains("## Message 1"));
        assert!(markdown.contains("**Role:** system"));
    }

    #[test]
    fn test_can_handle() {
        let store = Arc::new(SessionStore::in_memory().unwrap());
        let handler = SaveSessionCommandHandler::new(store, test_config());

        assert!(handler.can_handle(&Command::SaveSession { filepath: None }));
        assert!(!handler.can_handle(&Command::CreateSession { title: None }));
    }
}