package web

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

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

// SubView 是订阅的展示视图（已算好状态、文案与进度）。
type SubView struct {
	store.Subscription
	Eval         domain.Eval
	StateLabel   string
	StateClass   string
	RemainText   string
	RemainShort  string
	PeriodText   string
	DueText      string
	Progress     int
	Checkin      *store.Checkin
	CheckinState string
	UnitLabel    string
	Today        string
	// CanCheckinToday 表示今天可以直接打卡（订阅在有效状态与区间内）
	CanCheckinToday bool
}

// AssigneeLabel 返回打手显示名；未指派时给灰字提示。
func (v SubView) AssigneeLabel() string {
	if v.AssigneeName == "" {
		return "未指派"
	}
	return v.AssigneeName
}

// AssigneeHex 返回打手颜色；未指派用中性灰。
func (v SubView) AssigneeHex() string {
	if v.AssigneeColor == "" {
		return "#8A8F98"
	}
	return v.AssigneeColor
}

// AssigneeNone 是否未指派。
func (v SubView) AssigneeNone() bool { return v.AssigneeName == "" }

func stateLabel(state string) (string, string) {
	switch state {
	case domain.StateActive:
		return "进行中", "active"
	case domain.StatePending:
		return "未开始", "pending"
	case domain.StatePaused:
		return "暂停中", "paused"
	case domain.StateExpired:
		return "已到期", "expired"
	case domain.StateUsedUp:
		return "次数用尽", "usedup"
	case domain.StateClosed:
		return "已结束", "closed"
	}
	return "未知", "unknown"
}

func newSubView(s store.Subscription, today time.Time, warnDays int) SubView {
	e := s.Eval(today, warnDays)
	label, class := stateLabel(e.State)
	v := SubView{
		Subscription: s,
		Eval:         e,
		StateLabel:   label,
		StateClass:   class,
		Today:        domain.Date(today),
	}
	if s.Season {
		v.UnitLabel = "赛季"
		if s.SeasonDone != "" {
			v.RemainText = "赛季已完成"
			v.RemainShort = "已完成"
			v.StateLabel = "赛季已完成"
			v.StateClass = "active"
		} else {
			v.RemainText = fmt.Sprintf("剩 %d 天", e.RemainingDays)
			v.RemainShort = fmt.Sprintf("%d 天", e.RemainingDays)
		}
		v.PeriodText = s.StartDate + " → " + s.EndDate
		return v
	}
	if s.Unit == domain.UnitDay {
		v.UnitLabel = "按日"
		v.RemainText = fmt.Sprintf("剩 %d 天", e.RemainingDays)
		v.RemainShort = fmt.Sprintf("%d 天", e.RemainingDays)
		v.PeriodText = s.StartDate + " → " + s.EndDate
		total := domain.DayDiff(domain.ParseDateOr(s.StartDate, today), domain.ParseDateOr(s.EndDate, today)) + 1
		if total > 0 {
			v.Progress = clampPct(e.RemainingDays * 100 / total)
		}
	} else {
		v.UnitLabel = "按次"
		v.RemainText = fmt.Sprintf("已完成 %d / %d 次", s.UsedCount, s.TotalCount)
		v.RemainShort = fmt.Sprintf("%d/%d 次", s.UsedCount, s.TotalCount)
		v.PeriodText = s.StartDate + " 起"
		if s.EndDate != "" {
			v.PeriodText += " · 有效期至 " + s.EndDate
		} else {
			v.PeriodText += " · 无有效期"
		}
		if s.TotalCount > 0 {
			v.Progress = clampPct(s.UsedCount * 100 / s.TotalCount)
			v.Progress = clampPct(e.RemainingCount * 100 / s.TotalCount)
		}
	}

	switch e.Level {
	case domain.LevelToday:
		v.DueText = "今天到期"
	case domain.LevelWarn:
		switch {
		case e.DaysLeft == 1:
			v.DueText = "明天到期"
		case e.DaysLeft > 1:
			v.DueText = fmt.Sprintf("%d 天后到期", e.DaysLeft)
		case s.Unit == domain.UnitDay:
			v.DueText = fmt.Sprintf("还剩 %d 天", e.RemainingDays)
		default:
			v.DueText = fmt.Sprintf("%d 天后到期", e.DaysLeft)
		}
	case domain.LevelExpired:
		if s.EndDate != "" {
			d := domain.DayDiff(domain.ParseDateOr(s.EndDate, today), today)
			if d > 0 {
				v.DueText = fmt.Sprintf("已过期 %d 天", d)
			} else {
				v.DueText = "已到期"
			}
		} else {
			v.DueText = "次数已用尽"
		}
	}
	// 今天能否打卡：进行中且（按日或有剩余次数）
	v.CanCheckinToday = e.State == domain.StateActive &&
		(s.Unit == domain.UnitDay || e.RemainingCount > 0)
	return v
}

func clampPct(v int) int {
	if v < 0 {
		return 0
	}
	if v > 100 {
		return 100
	}
	return v
}

func subViews(subs []store.Subscription, today time.Time, warnDays int) []SubView {
	out := make([]SubView, 0, len(subs))
	for _, s := range subs {
		out = append(out, newSubView(s, today, warnDays))
	}
	return out
}

// ---------- 追加面板 ----------

// ExtendPanel 是「追加时长/次数」面板数据。
type ExtendPanel struct {
	Sub           store.Subscription
	View          SubView
	IsDay         bool
	Today         string
	OldEnd        string
	Base          string
	Suggested     string
	SuggestedDays int
	Back          string
	Months        []MiniMonth
	DefaultAmount int
}

// MiniMonth 是面板内的迷你月历。
type MiniMonth struct {
	Title string
	Weeks [][]MiniDay
}

// MiniDay 是迷你月历的一天。
type MiniDay struct {
	Date      string
	Day       int
	InMonth   bool
	IsOldEnd  bool
	IsToday   bool
	Disabled  bool
	IsWeekend bool
}

func buildExtendPanel(s *store.Subscription, pkg *store.Package, today time.Time, back string, warnDays int) *ExtendPanel {
	p := &ExtendPanel{
		Sub:           *s,
		View:          newSubView(*s, today, warnDays),
		IsDay:         s.Unit == domain.UnitDay,
		Today:         domain.Date(today),
		Back:          back,
		DefaultAmount: pkg.DefaultAmount,
	}
	if p.DefaultAmount <= 0 {
		p.DefaultAmount = 30
	}
	if s.Unit != domain.UnitDay {
		return p
	}
	oldEnd := domain.ParseDateOr(s.EndDate, today)
	plan := domain.PlanExtend(oldEnd, oldEnd, today)
	suggested := domain.AddDays(plan.Base, p.DefaultAmount-1)
	p.OldEnd = domain.Date(oldEnd)
	p.Base = domain.Date(plan.Base)
	p.Suggested = domain.Date(suggested)
	p.SuggestedDays = p.DefaultAmount

	anchor := oldEnd
	if anchor.Before(today) {
		anchor = today
	}
	sy, sm := anchor.Year(), anchor.Month()
	for i := 0; i < 3; i++ {
		mm := time.Month(int(sm) + i)
		y := sy
		for mm > 12 {
			mm -= 12
			y++
		}
		p.Months = append(p.Months, buildMiniMonth(y, mm, plan.Base, oldEnd, today))
	}
	return p
}

func buildMiniMonth(y int, m time.Month, base, oldEnd, today time.Time) MiniMonth {
	first := domain.MonthStart(y, m)
	last := domain.MonthEnd(y, m)
	start := domain.AddDays(first, -domain.WeekdayIndex(first))
	end := domain.AddDays(last, 7-domain.WeekdayIndex(last)-1)
	if domain.WeekdayIndex(last) == 6 {
		end = last
	}
	mm := MiniMonth{Title: fmt.Sprintf("%d 年 %d 月", y, int(m))}
	var week []MiniDay
	for d := start; !d.After(end); d = domain.AddDays(d, 1) {
		md := MiniDay{
			Date:      domain.Date(d),
			Day:       d.Day(),
			InMonth:   d.Month() == m,
			IsOldEnd:  domain.Date(d) == domain.Date(oldEnd),
			IsToday:   domain.Date(d) == domain.Date(today),
			Disabled:  d.Before(base),
			IsWeekend: d.Weekday() == time.Saturday || d.Weekday() == time.Sunday,
		}
		week = append(week, md)
		if len(week) == 7 {
			mm.Weeks = append(mm.Weeks, week)
			week = nil
		}
	}
	if len(week) > 0 {
		mm.Weeks = append(mm.Weeks, week)
	}
	return mm
}

// ---------- 时间轴 ----------

// Timeline 是客户订阅的时间轴（签带）。
type Timeline struct {
	Start string
	End   string
	Ticks []Tick
	Bars  []Bar
}

// Tick 是时间轴刻度。
type Tick struct {
	Label string
	Left  float64
}

// Bar 是一条订阅签带。
type Bar struct {
	SubID   int64
	Name    string
	Color   string
	Left    float64
	Width   float64
	DueLeft float64
	Label   string
	State   string
	Pauses  []BarPause
	HasDue  bool
}

// BarPause 是签带上的暂停灰段。
type BarPause struct {
	Left  float64
	Width float64
}

func buildTimeline(subs []store.Subscription, pauses map[int64][]store.Pause, today time.Time) *Timeline {
	if len(subs) == 0 {
		return nil
	}
	start := today
	end := today
	for _, s := range subs {
		st := domain.ParseDateOr(s.StartDate, today)
		if st.Before(start) {
			start = st
		}
		en := st.AddDate(0, 0, 30)
		if s.EndDate != "" {
			en = domain.ParseDateOr(s.EndDate, en)
		}
		if en.After(end) {
			end = en
		}
	}
	start = domain.AddDays(start, -7)
	end = domain.AddDays(end, 14)
	totalDays := domain.DayDiff(start, end) + 1
	if totalDays <= 0 {
		return nil
	}
	pos := func(t time.Time) float64 {
		return float64(domain.DayDiff(start, t)) / float64(totalDays) * 100
	}

	tl := &Timeline{Start: domain.Date(start), End: domain.Date(end)}

	// 月刻度
	cur := domain.MonthStart(start.Year(), start.Month())
	if cur.Before(start) {
		cur = cur.AddDate(0, 1, 0)
	}
	for !cur.After(end) {
		tl.Ticks = append(tl.Ticks, Tick{
			Label: fmt.Sprintf("%d.%02d", cur.Year(), int(cur.Month())),
			Left:  pos(cur),
		})
		cur = cur.AddDate(0, 1, 0)
	}

	for _, s := range subs {
		st := domain.ParseDateOr(s.StartDate, today)
		en := st.AddDate(0, 0, 30)
		if s.EndDate != "" {
			en = domain.ParseDateOr(s.EndDate, en)
		}
		if en.Before(st) {
			en = st
		}
		b := Bar{
			SubID:  s.ID,
			Name:   s.PackageName,
			Color:  s.PackageColor,
			Left:   pos(st),
			Width:  float64(domain.DayDiff(st, en)+1) / float64(totalDays) * 100,
			Label:  domain.Date(st) + " → " + domain.Date(en),
			State:  s.Status,
			HasDue: s.EndDate != "",
		}
		b.DueLeft = pos(en)
		if b.Width < 0.8 {
			b.Width = 0.8
		}
		for _, p := range pauses[s.ID] {
			ps := domain.ParseDateOr(p.StartDate, st)
			var pe time.Time
			if p.EndDate != "" {
				pe = domain.ParseDateOr(p.EndDate, today)
			} else {
				pe = today
			}
			if pe.Before(ps) {
				pe = ps
			}
			if ps.Before(st) {
				ps = st
			}
			if pe.After(en) {
				pe = en
			}
			if pe.Before(ps) {
				continue
			}
			b.Pauses = append(b.Pauses, BarPause{
				Left:  pos(ps),
				Width: float64(domain.DayDiff(ps, pe)+1) / float64(totalDays) * 100,
			})
		}
		tl.Bars = append(tl.Bars, b)
	}
	sort.Slice(tl.Bars, func(i, j int) bool { return tl.Bars[i].SubID < tl.Bars[j].SubID })
	return tl
}

// ---------- 分页 ----------

// Pager 是分页控件数据。
type Pager struct {
	Page  int
	Pages int
	Total int
	Prev  string
	Next  string
	From  int
	To    int
}

func newPager(r *http.Request, pageNo, perPage, total int) Pager {
	pages := (total + perPage - 1) / perPage
	if pages < 1 {
		pages = 1
	}
	if pageNo < 1 {
		pageNo = 1
	}
	if pageNo > pages {
		pageNo = pages
	}
	mk := func(n int) string {
		q := url.Values{}
		for k, v := range r.URL.Query() {
			q[k] = v
		}
		q.Set("page", strconv.Itoa(n))
		return r.URL.Path + "?" + q.Encode()
	}
	p := Pager{Page: pageNo, Pages: pages, Total: total}
	p.From = (pageNo-1)*perPage + 1
	if total == 0 {
		p.From = 0
	}
	p.To = pageNo * perPage
	if p.To > total {
		p.To = total
	}
	if pageNo > 1 {
		p.Prev = mk(pageNo - 1)
	}
	if pageNo < pages {
		p.Next = mk(pageNo + 1)
	}
	return p
}