package handlers

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"everypublish/server/internal/api/response"
	"everypublish/server/internal/models"
	"everypublish/server/internal/task"
	"everypublish/server/internal/ws"
)

// TaskHandler 发布任务处理器（状态机见 internal/task）
type TaskHandler struct {
	DB         *gorm.DB
	Dispatcher *ws.Dispatcher
}

type taskReq struct {
	Title       string   `json:"title" binding:"required"`
	Content     string   `json:"content"`
	Tags        []string `json:"tags"`
	AccountIDs  []uint64 `json:"accountIds"`
	MaterialIDs []uint64 `json:"materialIds"`
	ScheduleAt  *int64   `json:"scheduleAt"`
	Priority    int      `json:"priority"`
}

func marshalJSONArray[T any](arr []T) string {
	raw, _ := json.Marshal(arr)
	if raw == nil {
		return "[]"
	}
	return string(raw)
}

func (h *TaskHandler) validateTargets(wsid uint64, accountIDs, materialIDs []uint64) error {
	var accounts []models.Account
	if err := h.DB.Where("workspace_id = ? and id in ? and status = ?", wsid, accountIDs, "active").Find(&accounts).Error; err != nil {
		return err
	}
	if len(accounts) != len(uniqueIDs(accountIDs)) {
		return fmt.Errorf("账号不存在、不属于当前工作区或尚未完成登录")
	}
	var materials []models.Material
	if err := h.DB.Where("workspace_id = ? and id in ? and status = ?", wsid, materialIDs, "ready").Find(&materials).Error; err != nil {
		return err
	}
	if len(materials) != len(uniqueIDs(materialIDs)) {
		return fmt.Errorf("素材不存在、未就绪或不属于当前工作区")
	}
	return nil
}

func uniqueIDs(values []uint64) []uint64 {
	seen := make(map[uint64]struct{}, len(values))
	result := make([]uint64, 0, len(values))
	for _, value := range values {
		if _, ok := seen[value]; ok {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	return result
}

func recordTaskEvent(db *gorm.DB, row *models.Task, eventType, message string, data interface{}) {
	raw := ""
	if data != nil {
		if encoded, err := json.Marshal(data); err == nil {
			raw = string(encoded)
		}
	}
	_ = db.Create(&models.TaskEvent{
		WorkspaceID: row.WorkspaceID,
		TaskID:      row.ID,
		Type:        eventType,
		Status:      row.Status,
		Message:     message,
		Data:        raw,
	}).Error
}

// List 任务列表（状态筛选 + 分页）
func (h *TaskHandler) List(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	size, _ := strconv.Atoi(c.DefaultQuery("size", "20"))
	if page < 1 {
		page = 1
	}
	if size < 1 || size > 300 {
		size = 20
	}
	q := h.DB.Model(&models.Task{}).Where("workspace_id = ?", c.GetUint64("wsid"))
	if s := c.Query("status"); s != "" {
		q = q.Where("status = ?", s)
	}
	if s := c.Query("schedule"); s != "" {
		if s == "scheduled" {
			q = q.Where("schedule_at is not null and schedule_at > ?", time.Now())
		} else if s == "immediate" {
			q = q.Where("schedule_at is null or schedule_at <= ?", time.Now())
		}
	}
	var total int64
	q.Count(&total)
	var list []models.Task
	q.Order("id desc").Offset((page - 1) * size).Limit(size).Find(&list)
	response.OK(c, gin.H{"list": list, "total": total, "page": page, "size": size})
}

// Create 新建任务（draft）
func (h *TaskHandler) Create(c *gin.Context) {
	var req taskReq
	if err := c.ShouldBindJSON(&req); err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法："+err.Error())
		return
	}
	if len(req.AccountIDs) == 0 {
		response.Fail(c, http.StatusBadRequest, 1001, "至少选择一个平台账号")
		return
	}
	if len(req.MaterialIDs) == 0 {
		response.Fail(c, http.StatusBadRequest, 1001, "至少选择一个素材")
		return
	}
	if err := h.validateTargets(c.GetUint64("wsid"), req.AccountIDs, req.MaterialIDs); err != nil {
		response.Fail(c, http.StatusBadRequest, 1004, err.Error())
		return
	}
	priority := req.Priority
	if priority < 1 || priority > 10 {
		priority = 5
	}
	row := models.Task{
		WorkspaceID: c.GetUint64("wsid"),
		Title:       req.Title,
		Content:     req.Content,
		Tags:        marshalJSONArray(req.Tags),
		AccountIDs:  marshalJSONArray(req.AccountIDs),
		MaterialIDs: marshalJSONArray(req.MaterialIDs),
		Status:      task.Draft,
		Priority:    priority,
		MaxRetry:    3,
		CreatedBy:   c.GetUint64("uid"),
	}
	if req.ScheduleAt != nil {
		ts := time.UnixMilli(*req.ScheduleAt)
		if !ts.After(time.Now()) {
			response.Fail(c, http.StatusBadRequest, 1001, "定时发布时间必须晚于当前时间")
			return
		}
		row.ScheduleAt = &ts
	}
	if err := h.DB.Create(&row).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "创建失败")
		return
	}
	recordTaskEvent(h.DB, &row, "created", "任务已创建", nil)
	response.Audit(c, "task.create", "task:"+itoa(row.ID), gin.H{"title": req.Title})
	response.OK(c, row)
}

// Events 返回任务时间线，并强制按 workspace 隔离。
func (h *TaskHandler) Events(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var events []models.TaskEvent
	if err = h.DB.Where("task_id = ? and workspace_id = ?", id, c.GetUint64("wsid")).Order("id asc").Find(&events).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "任务时间线加载失败")
		return
	}
	response.OK(c, gin.H{"list": events})
}

// Get 任务详情
func (h *TaskHandler) Get(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var row models.Task
	if err = h.DB.Where("id = ? and workspace_id = ?", id, c.GetUint64("wsid")).First(&row).Error; err != nil {
		response.Fail(c, http.StatusNotFound, 1004, "任务不存在")
		return
	}
	response.OK(c, row)
}

// Update 编辑草稿（仅 draft/rejected）
func (h *TaskHandler) Update(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var req taskReq
	if err = c.ShouldBindJSON(&req); err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var row models.Task
	if err = h.DB.Where("id = ? and workspace_id = ?", id, c.GetUint64("wsid")).First(&row).Error; err != nil {
		response.Fail(c, http.StatusNotFound, 1004, "任务不存在")
		return
	}
	if row.Status != task.Draft && row.Status != task.Rejected {
		response.Fail(c, http.StatusConflict, 3005, "仅草稿或已驳回任务可编辑")
		return
	}
	if len(req.AccountIDs) == 0 || len(req.MaterialIDs) == 0 {
		response.Fail(c, http.StatusBadRequest, 1001, "至少选择一个账号和素材")
		return
	}
	if err := h.validateTargets(c.GetUint64("wsid"), req.AccountIDs, req.MaterialIDs); err != nil {
		response.Fail(c, http.StatusBadRequest, 1004, err.Error())
		return
	}
	updates := map[string]interface{}{
		"title":        req.Title,
		"content":      req.Content,
		"tags":         marshalJSONArray(req.Tags),
		"account_ids":  marshalJSONArray(req.AccountIDs),
		"material_ids": marshalJSONArray(req.MaterialIDs),
	}
	if req.ScheduleAt != nil {
		ts := time.UnixMilli(*req.ScheduleAt)
		if !ts.After(time.Now()) {
			response.Fail(c, http.StatusBadRequest, 1001, "定时发布时间必须晚于当前时间")
			return
		}
		updates["schedule_at"] = &ts
	} else {
		// nil represents an explicit immediate schedule in the JSON contract.
		// The update endpoint has no meaningful partial-update semantics.
		updates["schedule_at"] = nil
	}
	if err = h.DB.Model(&row).Updates(updates).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "更新失败")
		return
	}
	response.Audit(c, "task.update", "task:"+itoa(id), gin.H{"title": req.Title})
	response.OK(c, nil)
}

// Delete 删除草稿
func (h *TaskHandler) Delete(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return
	}
	var row models.Task
	if err = h.DB.Where("id = ? and workspace_id = ?", id, c.GetUint64("wsid")).First(&row).Error; err != nil {
		response.Fail(c, http.StatusNotFound, 1004, "任务不存在")
		return
	}
	if row.Status != task.Draft {
		response.Fail(c, http.StatusConflict, 3005, "仅草稿可删除")
		return
	}
	if err = h.DB.Delete(&row).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "删除失败")
		return
	}
	response.Audit(c, "task.delete", "task:"+itoa(id), nil)
	response.OK(c, nil)
}

// apply 状态转移并落库
func (h *TaskHandler) apply(c *gin.Context, action task.Action, extra map[string]interface{}) *models.Task {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		response.Fail(c, http.StatusBadRequest, 1001, "参数不合法")
		return nil
	}
	var row models.Task
	if err = h.DB.Where("id = ? and workspace_id = ?", id, c.GetUint64("wsid")).First(&row).Error; err != nil {
		response.Fail(c, http.StatusNotFound, 1004, "任务不存在")
		return nil
	}
	next, ok := task.Next(row.Status, action)
	if !ok {
		response.Fail(c, http.StatusConflict, 3005, "当前状态("+row.Status+")不允许该操作("+string(action)+")")
		return nil
	}
	updates := map[string]interface{}{"status": next}
	for k, v := range extra {
		updates[k] = v
	}
	if err = h.DB.Model(&row).Updates(updates).Error; err != nil {
		response.Fail(c, http.StatusInternalServerError, 5000, "更新失败")
		return nil
	}
	row.Status = next
	recordTaskEvent(h.DB, &row, string(action), "状态变更为 "+next, extra)
	return &row
}

// Submit 提交审核
func (h *TaskHandler) Submit(c *gin.Context) {
	if row := h.apply(c, task.ActionSubmit, nil); row != nil {
		response.Audit(c, "task.submit", "task:"+itoa(row.ID), nil)
		response.OK(c, row)
	}
}

// Approve 审核通过 → queued
func (h *TaskHandler) Approve(c *gin.Context) {
	if row := h.apply(c, task.ActionApprove, nil); row != nil {
		_ = Notify(h.DB, c.GetUint64("wsid"), []uint64{row.CreatedBy}, "task", "任务已通过审核", row.Title)
		if h.Dispatcher != nil && h.Dispatcher.Hub != nil {
			h.Dispatcher.Hub.BroadcastWS(row.WorkspaceID, "notification.new", gin.H{"kind": "task", "title": "任务已通过审核", "content": row.Title})
		}
		response.Audit(c, "task.approve", "task:"+itoa(row.ID), nil)
		if h.Dispatcher != nil {
			_ = h.Dispatcher.TryDispatch(row.ID)
			// TryDispatch can synchronously advance a Web-only mock task. Return
			// the persisted state instead of the stale queued copy from apply.
			_ = h.DB.Where("id = ? and workspace_id = ?", row.ID, row.WorkspaceID).First(row).Error
		}
		response.OK(c, row)
	}
}

// Reject 驳回（附批注）
func (h *TaskHandler) Reject(c *gin.Context) {
	var req struct {
		Note string `json:"note"`
	}
	_ = c.ShouldBindJSON(&req)
	if row := h.apply(c, task.ActionReject, map[string]interface{}{"review_note": req.Note, "reviewed_by": c.GetUint64("uid")}); row != nil {
		_ = Notify(h.DB, c.GetUint64("wsid"), []uint64{row.CreatedBy}, "task", "任务被驳回", req.Note)
		if h.Dispatcher != nil && h.Dispatcher.Hub != nil {
			h.Dispatcher.Hub.BroadcastWS(row.WorkspaceID, "notification.new", gin.H{"kind": "task", "title": "任务被驳回", "content": req.Note})
		}
		response.Audit(c, "task.reject", "task:"+itoa(row.ID), gin.H{"note": req.Note})
		response.OK(c, row)
	}
}

// Resubmit 驳回后重新提交
func (h *TaskHandler) Resubmit(c *gin.Context) {
	if row := h.apply(c, task.ActionResubmit, nil); row != nil {
		response.Audit(c, "task.resubmit", "task:"+itoa(row.ID), nil)
		response.OK(c, row)
	}
}

// Retry 失败重试
func (h *TaskHandler) Retry(c *gin.Context) {
	if row := h.apply(c, task.ActionRetry, map[string]interface{}{"error_message": ""}); row != nil {
		response.Audit(c, "task.retry", "task:"+itoa(row.ID), nil)
		if h.Dispatcher != nil {
			_ = h.Dispatcher.TryDispatch(row.ID)
		}
		response.OK(c, row)
	}
}

// Cancel 取消
func (h *TaskHandler) Cancel(c *gin.Context) {
	if row := h.apply(c, task.ActionCancel, nil); row != nil {
		if h.Dispatcher != nil {
			h.Dispatcher.Cancel(row.ID)
		}
		response.Audit(c, "task.cancel", "task:"+itoa(row.ID), nil)
		response.OK(c, row)
	}
}