use chrono::{DateTime, Utc};
use sqlx::{FromRow, SqlitePool};

use crate::{
    error::{ApiError, ApiResult},
    runs::model::{RunListQuery, RunStatus, RunTrigger, TaskRunListResponse, TaskRunResponse},
};

const DEFAULT_PAGE_SIZE: u32 = 20;
const MAX_PAGE_SIZE: u32 = 100;

#[derive(Debug, FromRow)]
struct TaskRunRow {
    id: i64,
    task_id: String,
    trigger_type: String,
    status: String,
    started_at: Option<DateTime<Utc>>,
    finished_at: Option<DateTime<Utc>>,
    duration_ms: Option<i64>,
    exit_code: Option<i64>,
    error_message: Option<String>,
    created_at: DateTime<Utc>,
}

impl TryFrom<TaskRunRow> for TaskRunResponse {
    type Error = ApiError;

    fn try_from(row: TaskRunRow) -> Result<Self, Self::Error> {
        Ok(Self {
            id: row.id,
            task_id: row.task_id,
            trigger: parse_trigger(&row.trigger_type)?,
            status: parse_status(&row.status)?,
            started_at: row.started_at,
            finished_at: row.finished_at,
            duration_ms: row
                .duration_ms
                .map(u64::try_from)
                .transpose()
                .map_err(ApiError::internal)?,
            exit_code: row
                .exit_code
                .map(i32::try_from)
                .transpose()
                .map_err(ApiError::internal)?,
            error_message: row.error_message,
            created_at: row.created_at,
        })
    }
}

pub async fn create_queued(
    pool: &SqlitePool,
    task_id: &str,
    trigger: RunTrigger,
) -> ApiResult<TaskRunResponse> {
    let now = Utc::now();
    let result = sqlx::query(
        "INSERT INTO task_runs (
            task_id, trigger_type, status, created_at
        ) VALUES (?, ?, ?, ?)",
    )
    .bind(task_id)
    .bind(trigger.as_str())
    .bind(RunStatus::Queued.as_str())
    .bind(now)
    .execute(pool)
    .await?;

    Ok(TaskRunResponse {
        id: result.last_insert_rowid(),
        task_id: task_id.to_owned(),
        trigger,
        status: RunStatus::Queued,
        started_at: None,
        finished_at: None,
        duration_ms: None,
        exit_code: None,
        error_message: None,
        created_at: now,
    })
}

pub async fn create_skipped(
    pool: &SqlitePool,
    task_id: &str,
    trigger: RunTrigger,
    message: &str,
) -> ApiResult<TaskRunResponse> {
    let now = Utc::now();
    let result = sqlx::query(
        "INSERT INTO task_runs (
            task_id, trigger_type, status, started_at, finished_at,
            duration_ms, error_message, created_at
        ) VALUES (?, ?, ?, ?, ?, 0, ?, ?)",
    )
    .bind(task_id)
    .bind(trigger.as_str())
    .bind(RunStatus::Skipped.as_str())
    .bind(now)
    .bind(now)
    .bind(message)
    .bind(now)
    .execute(pool)
    .await?;

    Ok(TaskRunResponse {
        id: result.last_insert_rowid(),
        task_id: task_id.to_owned(),
        trigger,
        status: RunStatus::Skipped,
        started_at: Some(now),
        finished_at: Some(now),
        duration_ms: Some(0),
        exit_code: None,
        error_message: Some(message.to_owned()),
        created_at: now,
    })
}

/// 返回是否真的更新到了运行记录；记录被删除（例如任务被删）时返回 false。
pub async fn mark_running(
    pool: &SqlitePool,
    run_id: i64,
    started_at: DateTime<Utc>,
) -> ApiResult<bool> {
    let result = sqlx::query("UPDATE task_runs SET status = ?, started_at = ? WHERE id = ?")
        .bind(RunStatus::Running.as_str())
        .bind(started_at)
        .bind(run_id)
        .execute(pool)
        .await?;
    Ok(result.rows_affected() > 0)
}

/// 返回是否真的更新到了运行记录。
pub async fn complete(
    pool: &SqlitePool,
    run_id: i64,
    status: RunStatus,
    finished_at: DateTime<Utc>,
    duration_ms: u64,
    exit_code: Option<i32>,
    error_message: Option<&str>,
) -> ApiResult<bool> {
    let result = sqlx::query(
        "UPDATE task_runs SET
            status = ?, finished_at = ?, duration_ms = ?,
            exit_code = ?, error_message = ?
        WHERE id = ?",
    )
    .bind(status.as_str())
    .bind(finished_at)
    .bind(duration_ms as i64)
    .bind(exit_code.map(i64::from))
    .bind(error_message)
    .bind(run_id)
    .execute(pool)
    .await?;
    Ok(result.rows_affected() > 0)
}

/// 启动时收敛上一次进程遗留下来的非终态运行，避免界面永远显示"运行中"。
pub async fn fail_interrupted_runs(pool: &SqlitePool) -> ApiResult<u64> {
    let result = sqlx::query(
        "UPDATE task_runs SET status = ?, finished_at = ?, error_message = ?
         WHERE status IN ('queued', 'running')",
    )
    .bind(RunStatus::Cancelled.as_str())
    .bind(Utc::now())
    .bind("TaskPilot 进程重启，运行被中断")
    .execute(pool)
    .await?;

    Ok(result.rows_affected())
}

pub async fn get(pool: &SqlitePool, run_id: i64) -> ApiResult<Option<TaskRunResponse>> {
    let row = sqlx::query_as::<_, TaskRunRow>(
        "SELECT
            id, task_id, trigger_type, status, started_at, finished_at,
            duration_ms, exit_code, error_message, created_at
        FROM task_runs
        WHERE id = ?",
    )
    .bind(run_id)
    .fetch_optional(pool)
    .await?;

    row.map(TaskRunResponse::try_from).transpose()
}

pub async fn list_for_task(
    pool: &SqlitePool,
    task_id: &str,
    query: RunListQuery,
) -> ApiResult<TaskRunListResponse> {
    let page = query.page.unwrap_or(1).max(1);
    let page_size = query
        .page_size
        .unwrap_or(DEFAULT_PAGE_SIZE)
        .clamp(1, MAX_PAGE_SIZE);
    let offset = i64::from(page - 1) * i64::from(page_size);
    let status = query.status.map(RunStatus::as_str);
    let trigger = query.trigger.map(RunTrigger::as_str);

    let total: i64 = sqlx::query_scalar(
        "SELECT COUNT(*) FROM task_runs
         WHERE task_id = ?
           AND (? IS NULL OR status = ?)
           AND (? IS NULL OR trigger_type = ?)",
    )
    .bind(task_id)
    .bind(status)
    .bind(status)
    .bind(trigger)
    .bind(trigger)
    .fetch_one(pool)
    .await?;
    let rows = sqlx::query_as::<_, TaskRunRow>(
        "SELECT
            id, task_id, trigger_type, status, started_at, finished_at,
            duration_ms, exit_code, error_message, created_at
        FROM task_runs
        WHERE task_id = ?
          AND (? IS NULL OR status = ?)
          AND (? IS NULL OR trigger_type = ?)
        ORDER BY created_at DESC, id DESC
        LIMIT ? OFFSET ?",
    )
    .bind(task_id)
    .bind(status)
    .bind(status)
    .bind(trigger)
    .bind(trigger)
    .bind(i64::from(page_size))
    .bind(offset)
    .fetch_all(pool)
    .await?;
    let items = rows
        .into_iter()
        .map(TaskRunResponse::try_from)
        .collect::<ApiResult<Vec<_>>>()?;

    Ok(TaskRunListResponse {
        items,
        page,
        page_size,
        total: u64::try_from(total).map_err(ApiError::internal)?,
    })
}

fn parse_trigger(value: &str) -> ApiResult<RunTrigger> {
    match value {
        "schedule" => Ok(RunTrigger::Schedule),
        "manual" => Ok(RunTrigger::Manual),
        "retry" => Ok(RunTrigger::Retry),
        _ => Err(ApiError::internal(format!("unknown run trigger: {value}"))),
    }
}

fn parse_status(value: &str) -> ApiResult<RunStatus> {
    match value {
        "queued" => Ok(RunStatus::Queued),
        "running" => Ok(RunStatus::Running),
        "succeeded" => Ok(RunStatus::Succeeded),
        "failed" => Ok(RunStatus::Failed),
        "timed_out" => Ok(RunStatus::TimedOut),
        "cancelled" => Ok(RunStatus::Cancelled),
        "skipped" => Ok(RunStatus::Skipped),
        _ => Err(ApiError::internal(format!("unknown run status: {value}"))),
    }
}