package web

import (
	"fmt"
	"net/http"
	"net/url"
	"sort"
	"time"

	"daili/internal/domain"
	"daili/internal/store"
)

// DayCell 是日历格。
type DayCell struct {
	Date       string
	Day        int
	InMonth    bool
	IsToday    bool
	IsWeekend  bool
	IsSelected bool
	IsPast     bool
	DueCount   int
	TaskCount  int
	DoneCount  int
	UrgentCnt  int
	Heat       int
	// PendingCount 当日还没完成的单数（= TaskCount - DoneCount）
	PendingCount int
	Tickets      []Ticket
	More         int
	// Strip 是左侧的打手色竖条（按出现顺序去重，未指派为灰）
	Strip []string
}

// Ticket 是日历格里的色签。
type Ticket struct {
	SubID   int64
	Tail    string
	Name    string
	Pkg     string
	Color   string
	Done    bool
	Skipped bool
	IsDue   bool
	Urgent  bool
	// AssigneeColor 打手颜色（未指派为空，模板用 spanAssignee 兜底）
	AssigneeColor string
}

// TaskRow 是当日待打清单的一行。
type TaskRow struct {
	SubView
	CheckinID int64
	Done      bool
	Skipped   bool
	Note      string
	Operator  string
	Urgent    bool
}

// PkgTab 是日历上方的套餐标签。
type PkgTab struct {
	ID    int64
	Name  string
	Color string
	Count int
}

type calendarData struct {
	Year, Month     int
	Title           string
	PrevY, PrevM    int
	NextY, NextM    int
	TodayStr        string
	Weekdays        []string
	Weeks           [][]DayCell
	Selected        string
	SelectedLabel   string
	SelectedIsToday bool
	SelectedIsPast  bool
	Tasks           []TaskRow
	TaskPending     int
	Due             []SubView
	OtherDue        []SubView
	Extend          *ExtendPanel
	MonthDue        int
	MonthTasks      int
	MonthDone       int
	MonthUrgent     int
	NoPackages      bool
	NoCustomers     bool
	Back            string

	// 套餐标签（在日历中独立显示的套餐）
	Tabs    []PkgTab
	PkgID   int64
	HasTabs bool

	// 快速完成：按尾号筛选出的候选
	PickTail string
	PickRows []TaskRow
	PickMsg  string
}

// calSub 是日历计算用的订阅上下文。
type calSub struct {
	sub    store.Subscription
	start  time.Time
	end    time.Time
	hasEnd bool
	eval   domain.Eval
	pauses []store.Pause
}

func (c calSub) pausedOn(date string) bool {
	for _, p := range c.pauses {
		if p.StartDate == "" {
			continue
		}
		if date >= p.StartDate && (p.EndDate == "" || date < p.EndDate) {
			return true
		}
	}
	return false
}

func (c calSub) covers(date string) bool {
	if c.sub.Status == domain.StatusClosed || !c.hasEnd {
		return false
	}
	if date < c.sub.StartDate || date > c.sub.EndDate {
		return false
	}
	if c.sub.Unit == domain.UnitCount && c.eval.RemainingCount <= 0 {
		return false
	}
	return !c.pausedOn(date)
}

// loadCalendarSubs 读取区间内与日历相交的订阅；pkgID>0 时只保留该套餐。
func (s *Server) loadCalendarSubs(from, to string, pkgID int64) ([]store.Subscription, map[int64][]store.Pause, map[int64]map[string]store.Checkin, map[int64]map[string]bool, error) {
	subs, err := s.db.CalendarSubs(from, to)
	if err != nil {
		return nil, nil, nil, nil, err
	}
	if pkgID > 0 {
		filtered := make([]store.Subscription, 0, len(subs))
		for _, sub := range subs {
			if sub.PackageID == pkgID {
				filtered = append(filtered, sub)
			}
		}
		subs = filtered
	}
	ids := make([]int64, 0, len(subs))
	for _, sub := range subs {
		ids = append(ids, sub.ID)
	}
	pauses, err := s.db.PausesForSubs(ids)
	if err != nil {
		return nil, nil, nil, nil, err
	}
	checkins, err := s.db.CheckinsBetween(from, to)
	if err != nil {
		return nil, nil, nil, nil, err
	}
	urgent, err := s.db.UrgentFlags(from, to)
	if err != nil {
		return nil, nil, nil, nil, err
	}
	return subs, pauses, checkins, urgent, nil
}

func (s *Server) handleCalendar(w http.ResponseWriter, r *http.Request) {
	today := domain.Today()
	y := s.queryInt(r, "y", today.Year())
	m := s.queryInt(r, "m", int(today.Month()))
	if m < 1 || m > 12 {
		y, m = today.Year(), int(today.Month())
	}
	monthStart := domain.MonthStart(y, time.Month(m))
	monthEnd := domain.MonthEnd(y, time.Month(m))

	pkgID := int64(s.queryInt(r, "pkg", 0))
	sel := r.URL.Query().Get("d")
	selT, err := domain.ParseDate(sel)
	if sel != "" && err != nil {
		sel = ""
	}
	if sel == "" {
		if today.After(monthEnd) || today.Before(monthStart) {
			sel = domain.Date(monthStart)
		} else {
			sel = domain.Date(today)
		}
		selT = domain.ParseDateOr(sel, today)
	}

	gridStart := domain.AddDays(monthStart, -domain.WeekdayIndex(monthStart))
	weeks := (domain.WeekdayIndex(monthStart) + monthEnd.Day() + 6) / 7
	gridEnd := domain.AddDays(gridStart, weeks*7-1)

	subs, pauses, checkins, urgent, err := s.loadCalendarSubs(domain.Date(gridStart), domain.Date(gridEnd), pkgID)
	if err != nil {
		http.Error(w, "读取订阅失败", http.StatusInternalServerError)
		return
	}

	warn := s.warnDays()
	list := make([]calSub, 0, len(subs))
	for _, sub := range subs {
		cs := calSub{
			sub:    sub,
			start:  domain.ParseDateOr(sub.StartDate, today),
			eval:   sub.Eval(today, warn),
			pauses: pauses[sub.ID],
		}
		if sub.EndDate != "" {
			cs.end = domain.ParseDateOr(sub.EndDate, today)
			cs.hasEnd = true
		}
		list = append(list, cs)
	}

	back := r.URL.RequestURI()
	data := &calendarData{
		Year: y, Month: m,
		Title:           fmt.Sprintf("%d 年 %d 月", y, m),
		TodayStr:        domain.Date(today),
		Weekdays:        []string{"一", "二", "三", "四", "五", "六", "日"},
		Selected:        sel,
		SelectedIsToday: sel == domain.Date(today),
		Back:            back,
		PkgID:           pkgID,
	}
	data.PrevY, data.PrevM = m-1, y
	if data.PrevM < 1 {
		data.PrevM = 12
		data.PrevY = y - 1
	}
	data.NextY, data.NextM = y, m+1
	if data.NextM > 12 {
		data.NextM = 1
		data.NextY = y + 1
	}
	data.SelectedLabel = selT.Format("1 月 2 日") + " 周" + dowCN(sel)
	data.SelectedIsPast = selT.Before(today)

	// 铺格子
	for wi := 0; wi < weeks; wi++ {
		week := make([]DayCell, 0, 7)
		for di := 0; di < 7; di++ {
			day := domain.AddDays(gridStart, wi*7+di)
			ds := domain.Date(day)
			cell := DayCell{
				Date:       ds,
				Day:        day.Day(),
				InMonth:    day.Month() == time.Month(m),
				IsToday:    ds == domain.Date(today),
				IsWeekend:  di >= 5,
				IsSelected: ds == sel,
				IsPast:     day.Before(today),
			}
			tickets := []Ticket{}
			for _, cs := range list {
				if cs.sub.EndDate == ds {
					cell.DueCount++
				}
				if !cell.InMonth || !cs.covers(ds) {
					continue
				}
				cell.TaskCount++
				ci := checkins[cs.sub.ID][ds]
				isUrgent := urgent[cs.sub.ID][ds]
				if isUrgent {
					cell.UrgentCnt++
				}
				t := Ticket{
					SubID:         cs.sub.ID,
					Tail:          cs.sub.CustomerTail,
					Name:          cs.sub.CustomerName,
					Pkg:           shortName(cs.sub.PackageName),
					Color:         cs.sub.PackageColor,
					Done:          ci.Status == "done",
					Skipped:       ci.Status == "skipped",
					IsDue:         cs.sub.EndDate == ds,
					Urgent:        isUrgent,
					AssigneeColor: cs.sub.AssigneeColor,
				}
				if t.Done || t.Skipped {
					cell.DoneCount++
				}
				tickets = append(tickets, t)
			}
			sort.SliceStable(tickets, func(i, j int) bool {
				if tickets[i].Urgent != tickets[j].Urgent {
					return tickets[i].Urgent
				}
				if tickets[i].Done != tickets[j].Done {
					return !tickets[i].Done
				}
				return tickets[i].SubID < tickets[j].SubID
			})
			// 竖条按“当天全部任务”算，不能被色签的 3 条上限截断
			cell.Strip = assigneeStrip(tickets)
			if len(tickets) > 3 {
				cell.More = len(tickets) - 3
				tickets = tickets[:3]
			}
			cell.Tickets = tickets
			cell.PendingCount = cell.TaskCount - cell.DoneCount
			cell.Heat = heatLevel(cell.TaskCount + cell.DueCount)
			if cell.InMonth {
				data.MonthDue += cell.DueCount
				data.MonthTasks += cell.TaskCount
				data.MonthDone += cell.DoneCount
				data.MonthUrgent += cell.UrgentCnt
			}
			week = append(week, cell)
		}
		data.Weeks = append(data.Weeks, week)
	}

	// 当日清单
	due := []SubView{}
	tasks := []TaskRow{}
	for _, cs := range list {
		if cs.sub.EndDate == sel {
			due = append(due, newSubView(cs.sub, today, warn))
		}
		if !cs.covers(sel) {
			continue
		}
		row := TaskRow{SubView: newSubView(cs.sub, today, warn), Urgent: urgent[cs.sub.ID][sel]}
		if ci, ok := checkins[cs.sub.ID][sel]; ok {
			row.CheckinID = ci.ID
			row.Done = ci.Status == "done"
			row.Skipped = ci.Status == "skipped"
			row.Note = ci.Note
			row.Operator = ci.OperatorName
		}
		tasks = append(tasks, row)
	}
	sortTasks(tasks)
	data.Tasks = tasks
	for _, row := range tasks {
		if !row.Done && !row.Skipped {
			data.TaskPending++
		}
	}
	data.Due = due

	// 其它日期到期（不在当天的 7 天内）
	if upcoming, err := s.db.RecentDue(domain.Date(today), 7); err == nil {
		for _, u := range upcoming {
			if u.EndDate == sel {
				continue
			}
			if pkgID > 0 && u.PackageID != pkgID {
				continue
			}
			data.OtherDue = append(data.OtherDue, newSubView(u, today, warn))
		}
	}

	// 套餐标签
	pkgs, _ := s.db.ListPackages(true)
	separate := []store.Package{}
	for _, p := range pkgs {
		if p.CalendarSeparate && !p.Archived {
			separate = append(separate, p)
		}
	}
	if len(separate) > 0 {
		data.HasTabs = true
		data.Tabs = append(data.Tabs, PkgTab{ID: 0, Name: "全部", Color: "#8A8F98", Count: len(list)})
		for _, p := range separate {
			cnt := 0
			for _, sub := range subs {
				if sub.PackageID == p.ID {
					cnt++
				}
			}
			data.Tabs = append(data.Tabs, PkgTab{ID: p.ID, Name: p.Name, Color: p.Color, Count: cnt})
		}
	}

	// 快速完成：按尾号列出候选
	if tail := r.URL.Query().Get("pick"); tail != "" {
		data.PickTail = tail
		for _, row := range tasks {
			if row.CustomerTail == tail {
				data.PickRows = append(data.PickRows, row)
			}
		}
		if len(data.PickRows) == 0 {
			data.PickMsg = "尾号 " + tail + " 在今天没有待完成的服务"
		}
	}

	// 追加面板
	if eid := s.queryInt(r, "extend", 0); eid > 0 {
		if sub, err := s.db.Sub(int64(eid)); err == nil {
			if pkg, err := s.db.Package(sub.PackageID); err == nil {
				data.Extend = buildExtendPanel(sub, pkg, today, back, warn)
			}
		}
	}

	if n, _ := s.db.CustomerCount(); n == 0 {
		data.NoCustomers = true
	}
	if len(pkgs) == 0 {
		data.NoPackages = true
	}

	p := s.newPage(r, "日历", "calendar")
	p.D = data
	s.render(w, r, "calendar", p)
}

// sortTasks 加急优先，其次未完成，最后按结束日。
func sortTasks(tasks []TaskRow) {
	sort.SliceStable(tasks, func(i, j int) bool {
		ai, aj := tasks[i], tasks[j]
		if ai.Urgent != aj.Urgent {
			return ai.Urgent
		}
		adi := ai.Done || ai.Skipped
		adj := aj.Done || aj.Skipped
		if adi != adj {
			return !adi
		}
		return ai.EndDate < aj.EndDate
	})
}

// assigneeStrip 把一格里所有任务的打手颜色去重后返回，未指派用灰色占位。
func assigneeStrip(tickets []Ticket) []string {
	if len(tickets) == 0 {
		return nil
	}
	seen := map[string]bool{}
	out := make([]string, 0, 4)
	for _, t := range tickets {
		c := t.AssigneeColor
		if c == "" {
			c = "#8A8F98"
		}
		if seen[c] {
			continue
		}
		seen[c] = true
		out = append(out, c)
	}
	return out
}

func heatLevel(n int) int {
	switch {
	case n <= 0:
		return 0
	case n <= 2:
		return 1
	case n <= 5:
		return 2
	case n <= 9:
		return 3
	default:
		return 4
	}
}

// shortName 取套餐名前两个字符，用作日历色签上的短标签。
func shortName(s string) string {
	r := []rune(s)
	if len(r) <= 2 {
		return s
	}
	return string(r[:2])
}

// stripParam 去掉地址里的某个参数，用于拼“返回”链接。
func stripParam(raw, key string) string {
	u, err := url.Parse(raw)
	if err != nil {
		return raw
	}
	q := u.Query()
	q.Del(key)
	u.RawQuery = q.Encode()
	return u.String()
}