#!/usr/bin/env python3
"""
任務執行模組
管理多架無人機的 GUIDED 模式飛行控制迴圈

設計:
    - 每架無人機持有一個航點序列，逐點推進
    - 各自到達就各自切換到下一個航點
    - 用 QTimer 驅動，在 Qt 主線程執行
    - 暫停 = 停止發送 setpoint，飛控自動懸停
    - 相容舊的 2 階段任務與新的多航點任務 (Grid Sweep)
"""
import math
from enum import Enum
from PyQt6.QtCore import QObject, QTimer, pyqtSignal


class MissionState(Enum):
    """整體任務狀態"""
    IDLE = "idle"
    RUNNING = "running"
    PAUSED = "paused"


class DroneTask:
    """單架無人機的任務資料"""
    __slots__ = ('drone_id', 'sysid', 'waypoints', 'wp_index', 'done')

    def __init__(self, drone_id, sysid, waypoints):
        """
        Args:
            drone_id: GUI 用的 ID (如 's0_11')
            sysid: MAVLink system ID (如 11)
            waypoints: 航點序列 [(lat, lon, alt), ...]
        """
        self.drone_id = drone_id
        self.sysid = sysid
        self.waypoints = waypoints
        self.wp_index = 0
        self.done = len(waypoints) == 0

    @property
    def current_target(self):
        if self.done or self.wp_index >= len(self.waypoints):
            return None
        return self.waypoints[self.wp_index]

    @property
    def total_waypoints(self):
        return len(self.waypoints)


class MissionExecutor(QObject):
    """
    任務執行器

    planned_waypoints 格式:
        {
            'drone_ids': ['s0_1', 's0_2', ...],
            'waypoints': [
                [(lat,lon,alt), ...],   # drone 0
                [(lat,lon,alt), ...],   # drone 1
            ]
        }
    """

    # 信號
    drone_waypoint_reached = pyqtSignal(str, int, int)  # (drone_id, wp_index, total)
    mission_completed = pyqtSignal()

    def __init__(self, sender, drone_gps,
                 arrival_radius=2.0, send_rate_hz=2.0):
        super().__init__()
        self.sender = sender
        self.drone_gps = drone_gps
        self.arrival_radius = arrival_radius
        self.state = MissionState.IDLE
        self.tasks = {}

        self._interval_ms = int(1000 / send_rate_hz)
        self._timer = QTimer()
        self._timer.timeout.connect(self._tick)

    # ------------------------------------------------------------------ 公開方法

    def start(self, planned_waypoints):
        """啟動任務"""
        if self.state == MissionState.RUNNING:
            print("任務已在執行中")
            return

        self.tasks.clear()

        drone_ids = planned_waypoints['drone_ids']
        waypoints_list = planned_waypoints['waypoints']

        for i, drone_id in enumerate(drone_ids):
            sysid = int(drone_id.split('_')[1])
            self.tasks[drone_id] = DroneTask(drone_id, sysid, waypoints_list[i])

        self.state = MissionState.RUNNING
        self._timer.start(self._interval_ms)

        total_wps = sum(t.total_waypoints for t in self.tasks.values())
        print(f"任務啟動: {len(self.tasks)} 架無人機, "
              f"共 {total_wps} 個航點, "
              f"到達半徑={self.arrival_radius}m, "
              f"發送週期={self._interval_ms}ms")

    def pause(self):
        """暫停任務"""
        if self.state == MissionState.RUNNING:
            self._timer.stop()
            self.state = MissionState.PAUSED
            print("任務暫停")

    def resume(self):
        """恢復任務"""
        if self.state == MissionState.PAUSED:
            self._timer.start(self._interval_ms)
            self.state = MissionState.RUNNING
            print("任務恢復")

    def stop(self):
        """停止任務"""
        self._timer.stop()
        self.tasks.clear()
        self.state = MissionState.IDLE
        print("任務停止")

    # ------------------------------------------------------------------ 控制迴圈

    def _tick(self):
        """控制迴圈"""
        all_done = True

        for task in self.tasks.values():
            if task.done:
                continue

            all_done = False
            target = task.current_target
            if target is None:
                continue

            # 讀取當前 GPS
            gps = self.drone_gps.get(task.drone_id)
            if gps is None:
                continue

            tgt_lat, tgt_lon, tgt_alt = target
            distance = _haversine(gps['lat'], gps['lon'], tgt_lat, tgt_lon)

            # 到達判定
            if distance < self.arrival_radius:
                task.wp_index += 1
                if task.wp_index >= task.total_waypoints:
                    task.done = True
                    self.drone_waypoint_reached.emit(
                        task.drone_id, task.wp_index, task.total_waypoints
                    )
                    print(f"  {task.drone_id} → DONE "
                          f"({task.total_waypoints}/{task.total_waypoints})")
                    continue
                else:
                    self.drone_waypoint_reached.emit(
                        task.drone_id, task.wp_index, task.total_waypoints
                    )
                    print(f"  {task.drone_id} → WP {task.wp_index}/{task.total_waypoints} "
                          f"(距離: {distance:.1f}m)")
                    # 更新目標
                    tgt_lat, tgt_lon, tgt_alt = task.current_target

            # 發送 setpoint
            self.sender.send_position_global(
                task.sysid, tgt_lat, tgt_lon, tgt_alt
            )

        # 全部完成檢查
        if all_done and self.tasks:
            self._timer.stop()
            self.state = MissionState.IDLE
            self.mission_completed.emit()
            print("===== 任務全部完成 =====")


# ------------------------------------------------------------------ 工具函式

def _haversine(lat1, lon1, lat2, lon2):
    """計算兩個 GPS 座標間的水平距離 (公尺)"""
    R = 6371000.0
    lat1_r = math.radians(lat1)
    lat2_r = math.radians(lat2)
    dlat = math.radians(lat2 - lat1)
    dlon = math.radians(lon2 - lon1)

    a = (math.sin(dlat / 2) ** 2 +
         math.cos(lat1_r) * math.cos(lat2_r) * math.sin(dlon / 2) ** 2)
    return R * 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))