package core

import (
	"ZhenTuLocalPassiveAdapter/config"
	"ZhenTuLocalPassiveAdapter/dto"
	"ZhenTuLocalPassiveAdapter/fs"
	"ZhenTuLocalPassiveAdapter/logger"
	"ZhenTuLocalPassiveAdapter/util"
	"context"
	"fmt"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	"go.uber.org/zap"
	"path"
	"time"
)

var tracer = otel.Tracer("task")

func HandleTask(ctx context.Context, device config.DeviceMapping, task dto.Task) (*dto.FileObject, error) {
	subCtx, span := tracer.Start(ctx, "HandleTask")
	defer span.End()
	adapter := fs.GetAdapter()
	span.SetAttributes(attribute.String("task.id", task.TaskID))
	span.SetAttributes(attribute.String("task", util.ToJson(task)))
	span.SetAttributes(attribute.String("device.no", device.DeviceNo))
	span.SetAttributes(attribute.String("device.name", device.Name))
	dateDirPath := path.Join(device.Name, task.StartTime.Format("2006"+config.Config.FileName.DateSeparator+"01"+config.Config.FileName.DateSeparator+"02"))
	fileList, usedTimePrefix, err := getFileListForTask(subCtx, adapter, dateDirPath, task)
	if err != nil {
		span.SetAttributes(attribute.String("error", err.Error()))
		span.SetStatus(codes.Error, "获取文件列表失败")
		logger.Error("获取文件列表失败",
			zap.String("deviceNo", device.DeviceNo),
			zap.Error(err))
		return nil, err
	}

	files := util.FilterAndSortFiles(subCtx, fileList, task.StartTime, task.EndTime)
	if len(files) == 0 {
		if usedTimePrefix {
			span.SetAttributes(attribute.Bool("fileList.fallback", true))
			fallbackFileList, err := adapter.GetFileList(subCtx, dateDirPath, task.StartTime)
			if err != nil {
				span.SetAttributes(attribute.String("error", err.Error()))
				span.SetStatus(codes.Error, "获取文件列表失败")
				return nil, err
			}
			fileList = fallbackFileList
			files = util.FilterAndSortFiles(subCtx, fileList, task.StartTime, task.EndTime)
		}
		if len(files) == 0 {
			span.SetStatus(codes.Error, "没有找到文件")
			return nil, fmt.Errorf("没有找到文件")
		}
	}
	span.SetAttributes(attribute.Int("fileCount", len(files)))

	// 如果过滤后的文件列表无法覆盖任务开始时间，说明“按小时前缀”可能漏掉了前一小时的尾巴片段，降级为按天目录列举
	if usedTimePrefix && files[0].StartTime.After(task.StartTime) {
		span.SetAttributes(attribute.Bool("fileList.fallback", true))
		fallbackFileList, err := adapter.GetFileList(subCtx, dateDirPath, task.StartTime)
		if err != nil {
			span.SetAttributes(attribute.String("error", err.Error()))
			span.SetStatus(codes.Error, "获取文件列表失败")
			return nil, err
		}
		fileList = fallbackFileList
		files = util.FilterAndSortFiles(subCtx, fileList, task.StartTime, task.EndTime)
		if len(files) == 0 {
			span.SetStatus(codes.Error, "没有找到文件")
			return nil, fmt.Errorf("没有找到文件")
		}
	}

	constructTask, err := util.CheckFileCoverageAndConstructTask(subCtx, files, task.StartTime, task.EndTime, task)
	if err != nil {
		if usedTimePrefix {
			span.SetAttributes(attribute.Bool("fileList.fallback", true))
			fallbackFileList, fallbackErr := adapter.GetFileList(subCtx, dateDirPath, task.StartTime)
			if fallbackErr != nil {
				span.SetAttributes(attribute.String("error", fallbackErr.Error()))
				span.SetStatus(codes.Error, "获取文件列表失败")
				return nil, fallbackErr
			}
			files = util.FilterAndSortFiles(subCtx, fallbackFileList, task.StartTime, task.EndTime)
			constructTask, err = util.CheckFileCoverageAndConstructTask(subCtx, files, task.StartTime, task.EndTime, task)
		}
		if err == nil {
			goto runFfmpeg
		}
		span.SetAttributes(attribute.String("error", err.Error()))
		span.SetStatus(codes.Error, "文件片段检查失败")
		logger.Error("文件片段检查失败",
			zap.String("deviceNo", device.DeviceNo),
			zap.Error(err))
		return nil, err
	}

runFfmpeg:
	ok := util.RunFfmpegTask(subCtx, constructTask)
	if !ok {
		span.SetAttributes(attribute.String("error", "ffmpeg任务执行失败"))
		span.SetStatus(codes.Error, "ffmpeg任务执行失败")
		return nil, fmt.Errorf("ffmpeg任务执行失败")
	}
	return &dto.FileObject{
		CreateTime:   task.EndTime,
		EndTime:      task.EndTime,
		NeedDownload: true,
		URL:          constructTask.OutputFile,
	}, nil
}

func getFileListForTask(ctx context.Context, adapter fs.Adapter, dateDirPath string, task dto.Task) ([]dto.File, bool, error) {
	storageType := config.Config.Record.Storage.Type
	if storageType != "s3" && storageType != "alioss" {
		fileList, err := adapter.GetFileList(ctx, dateDirPath, task.StartTime)
		return fileList, false, err
	}

	lookBack := time.Duration(config.Config.Record.Duration) * time.Second
	if lookBack < time.Minute {
		lookBack = time.Minute
	}
	earliestStart := task.StartTime.Add(-lookBack)
	if !isSameDate(earliestStart, task.StartTime) {
		earliestStart = task.StartTime
	}
	if !isSameDate(task.EndTime, task.StartTime) {
		// 约束：按业务约定不跨天；如果出现跨天，直接回退到按天目录列举（但仍只列举开始日期目录）
		fileList, err := adapter.GetFileList(ctx, dateDirPath, task.StartTime)
		return fileList, false, err
	}

	startHour := earliestStart.Hour()
	endHour := task.EndTime.Hour()
	if endHour < startHour {
		// 理论上只有跨天才会出现；按业务约定不跨天，直接回退
		fileList, err := adapter.GetFileList(ctx, dateDirPath, task.StartTime)
		return fileList, false, err
	}

	seen := make(map[string]struct{}, (endHour-startHour+1)*512)
	var result []dto.File
	for hour := startHour; hour <= endHour; hour++ {
		hourPrefix := fmt.Sprintf("%02d", hour)
		dirPathWithHourPrefix := path.Join(dateDirPath, hourPrefix)
		fileList, err := adapter.GetFileList(ctx, dirPathWithHourPrefix, task.StartTime)
		if err != nil {
			return nil, true, err
		}
		for _, file := range fileList {
			key := file.Path + "/" + file.Name
			if _, ok := seen[key]; ok {
				continue
			}
			seen[key] = struct{}{}
			result = append(result, file)
		}
	}
	return result, true, nil
}

func isSameDate(a, b time.Time) bool {
	return a.Year() == b.Year() && a.Month() == b.Month() && a.Day() == b.Day()
}