package ui

import (
	"fmt"
	"image"
	"image/color"
	"log"
	"os"
	"strings"
	"sync"
	"time"

	"gioui.org/app"
	"gioui.org/font/gofont"
	"gioui.org/layout"
	"gioui.org/op"
	"gioui.org/op/clip"
	"gioui.org/op/paint"
	"gioui.org/text"
	"gioui.org/unit"
	"gioui.org/widget"
	"gioui.org/widget/material"

	"silverpose/v2/internal/alert"
	"silverpose/v2/internal/fall"
	"silverpose/v2/internal/monitor"
)

const galleryCapacity = 9 // 3 columns x 3 rows

// Light Windows theme tokens (see docs/ui/silver-pose-ui-ux-spec.md).
var (
	colorBg      = color.NRGBA{R: 0xEA, G: 0xF1, B: 0xF8, A: 0xFF}
	colorSurface = color.NRGBA{R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF}
	colorText    = color.NRGBA{R: 0x1E, G: 0x29, B: 0x3B, A: 0xFF}
	colorSubtle  = color.NRGBA{R: 0x52, G: 0x65, B: 0x7C, A: 0xFF}
	colorAccent  = color.NRGBA{R: 0x25, G: 0x63, B: 0xEB, A: 0xFF}
	colorAlert   = color.NRGBA{R: 0xC6, G: 0x28, B: 0x28, A: 0xFF}
	colorScrim   = color.NRGBA{A: 0xB0}
)

type Settings struct {
	SourceEnvironment string
	ModelSHA256       string
	RuntimeSummary    string
	EventSummary      string
}

type Commands struct {
	Start func()
	Stop  func()
}

// galleryIncoming is a confirmed screenshot queued off the UI thread. The Gio
// op is built once on the UI thread when it is promoted into galleryItem.
type galleryIncoming struct {
	caption string
	image   *image.RGBA
}

type galleryItem struct {
	caption   string
	op        paint.ImageOp
	click     widget.Clickable
	lastClick time.Time
}

// Window observes monitor updates. Background goroutines call Present/
// PresentAlert/ReportIssue, which only mutate shared state under a lock and
// Invalidate; the Gio event loop reads that state and renders.
type Window struct {
	appWindow *app.Window
	theme     *material.Theme
	settings  Settings
	commands  Commands
	spec      WindowSpec

	mu          sync.Mutex
	model       ViewModel
	latestImage *image.RGBA
	imageGen    uint64
	pending     *alert.Record
	seenAlerts  map[string]struct{}
	incoming    []galleryIncoming
	seenEvents  map[string]struct{}

	// Touched only by the event-loop goroutine.
	imageOp       paint.ImageOp
	imageShownGen uint64
	tabs          []string
	tabButton     []widget.Clickable
	active        int
	startButton   widget.Clickable
	stopButton    widget.Clickable
	ackButton     widget.Clickable
	gallery       []*galleryItem
	viewing       *galleryItem
	viewerClose   widget.Clickable
}

func NewWindow(settings Settings, commands Commands) (*Window, error) {
	spec := MonitorWindowSpec()
	theme := material.NewTheme()
	theme.Shaper = text.NewShaper(text.WithCollection(gofont.Collection()))
	theme.Palette.Bg = colorBg
	theme.Palette.Fg = colorText
	theme.Palette.ContrastBg = colorAccent
	theme.Palette.ContrastFg = color.NRGBA{R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF}

	model := NewViewModel()
	model.SetSourceReady(settings.SourceEnvironment, settings.SourceEnvironment != "")

	appWindow := new(app.Window)
	appWindow.Option(
		app.Title(spec.Title),
		app.Size(unit.Dp(spec.Width), unit.Dp(spec.Height)),
		app.MinSize(unit.Dp(960), unit.Dp(640)),
	)
	window := &Window{
		appWindow:  appWindow,
		theme:      theme,
		settings:   settings,
		commands:   commands,
		spec:       spec,
		model:      model,
		seenAlerts: make(map[string]struct{}),
		seenEvents: make(map[string]struct{}),
		tabs:       []string{"监控", "设置"},
	}
	window.tabButton = make([]widget.Clickable, len(window.tabs))
	return window, nil
}

func (window *Window) Run() int {
	go func() {
		err := window.loop()
		window.stop()
		if err != nil {
			log.Print(err)
		}
		os.Exit(0)
	}()
	app.Main()
	return 0
}

func (window *Window) loop() error {
	var ops op.Ops
	for {
		switch event := window.appWindow.Event().(type) {
		case app.DestroyEvent:
			return event.Err
		case app.FrameEvent:
			gtx := app.NewContext(&ops, event)
			window.layout(gtx)
			event.Frame(gtx.Ops)
		}
	}
}

func (window *Window) start() {
	if window.commands.Start != nil {
		window.commands.Start()
	}
}

func (window *Window) stop() {
	if window.commands.Stop != nil {
		window.commands.Stop()
	}
}

// Present stores the newest analysed frame and queues any confirmed screenshot.
func (window *Window) Present(update monitor.Update) {
	window.mu.Lock()
	state := highestState(update.Result)
	window.model.Apply(state, update.SourceStatus)
	if update.SourceMessage != "" {
		window.model.ConnectionText = "视频流：" + update.SourceMessage
	}
	if update.Image != nil {
		window.latestImage = update.Image
		window.imageGen++
	}
	if update.Image != nil {
		for _, record := range update.Events {
			id := record.Event.EventID
			if id == "" {
				continue
			}
			if _, seen := window.seenEvents[id]; seen {
				continue
			}
			window.seenEvents[id] = struct{}{}
			window.incoming = append(window.incoming, galleryIncoming{
				caption: fmt.Sprintf("%s %s", record.Event.TrackID, time.Now().Format("15:04:05")),
				image:   update.Image,
			})
		}
	}
	window.mu.Unlock()
	window.appWindow.Invalidate()
}

// PresentAlert queues one confirm popup per event ID and plays the alert sound.
func (window *Window) PresentAlert(record alert.Record) {
	if !record.Written {
		return
	}
	window.mu.Lock()
	if _, seen := window.seenAlerts[record.Event.EventID]; seen {
		window.mu.Unlock()
		return
	}
	window.seenAlerts[record.Event.EventID] = struct{}{}
	queued := record
	window.pending = &queued
	window.mu.Unlock()
	playAlertSound()
	window.appWindow.Invalidate()
}

// ReportIssue surfaces a recoverable startup/worker issue without red fall
// language or exposing configuration values.
func (window *Window) ReportIssue(message string) {
	window.mu.Lock()
	window.model.ConnectionText = "视频流：" + message
	window.model.Critical = false
	window.model.StateText = "检测状态：正常"
	window.mu.Unlock()
	window.appWindow.Invalidate()
}

func (window *Window) layout(gtx layout.Context) layout.Dimensions {
	paint.Fill(gtx.Ops, colorBg)

	window.mu.Lock()
	model := window.model
	frame := window.latestImage
	gen := window.imageGen
	pending := window.pending
	incoming := window.incoming
	window.incoming = nil
	window.mu.Unlock()

	for i := range incoming {
		item := &galleryItem{caption: incoming[i].caption, op: paint.NewImageOp(incoming[i].image)}
		window.gallery = append([]*galleryItem{item}, window.gallery...)
	}
	if len(window.gallery) > galleryCapacity {
		window.gallery = window.gallery[:galleryCapacity]
	}

	hasFrame := frame != nil
	if hasFrame && gen != window.imageShownGen {
		window.imageOp = paint.NewImageOp(frame)
		window.imageShownGen = gen
	}

	now := time.Now()
	for _, item := range window.gallery {
		if item.click.Clicked(gtx) {
			if !item.lastClick.IsZero() && now.Sub(item.lastClick) < 350*time.Millisecond {
				window.viewing = item
			}
			item.lastClick = now
		}
	}
	if window.viewerClose.Clicked(gtx) {
		window.viewing = nil
	}
	if window.ackButton.Clicked(gtx) {
		window.mu.Lock()
		window.pending = nil
		window.mu.Unlock()
		pending = nil
	}

	content := func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			layout.Rigid(window.layoutTabs),
			layout.Flexed(1, func(gtx layout.Context) layout.Dimensions {
				if window.active == 0 {
					return window.layoutMonitor(gtx, model, hasFrame)
				}
				return window.layoutSettings(gtx, model)
			}),
		)
	}

	children := []layout.StackChild{layout.Expanded(content)}
	if window.viewing != nil {
		children = append(children, layout.Expanded(scrim), layout.Expanded(window.layoutViewer))
	}
	if pending != nil {
		record := *pending
		children = append(children,
			layout.Expanded(scrim),
			layout.Stacked(func(gtx layout.Context) layout.Dimensions {
				return layout.Center.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
					return window.layoutDialog(gtx, record)
				})
			}),
		)
	}
	if len(children) == 1 {
		return content(gtx)
	}
	return layout.Stack{}.Layout(gtx, children...)
}

func scrim(gtx layout.Context) layout.Dimensions {
	paint.FillShape(gtx.Ops, colorScrim, clip.Rect{Max: gtx.Constraints.Min}.Op())
	return layout.Dimensions{Size: gtx.Constraints.Min}
}

func (window *Window) layoutTabs(gtx layout.Context) layout.Dimensions {
	for i := range window.tabButton {
		if window.tabButton[i].Clicked(gtx) {
			window.active = i
		}
	}
	children := make([]layout.FlexChild, 0, len(window.tabs))
	for i := range window.tabs {
		i := i
		children = append(children, layout.Rigid(func(gtx layout.Context) layout.Dimensions {
			button := material.Button(window.theme, &window.tabButton[i], window.tabs[i])
			if i != window.active {
				button.Background = colorSurface
				button.Color = colorSubtle
			}
			return layout.UniformInset(unit.Dp(6)).Layout(gtx, button.Layout)
		}))
	}
	return layout.Flex{}.Layout(gtx, children...)
}

func (window *Window) layoutMonitor(gtx layout.Context, model ViewModel, hasFrame bool) layout.Dimensions {
	return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
		layout.Flexed(3, func(gtx layout.Context) layout.Dimensions {
			return layout.UniformInset(unit.Dp(8)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
				if !hasFrame {
					return layout.Center.Layout(gtx, material.Body1(window.theme, model.ConnectionText).Layout)
				}
				return widget.Image{Src: window.imageOp, Fit: widget.Contain, Position: layout.Center}.Layout(gtx)
			})
		}),
		layout.Flexed(2, func(gtx layout.Context) layout.Dimensions {
			return window.layoutRightPanel(gtx, model)
		}),
	)
}

func (window *Window) layoutRightPanel(gtx layout.Context, model ViewModel) layout.Dimensions {
	if window.startButton.Clicked(gtx) {
		window.start()
	}
	if window.stopButton.Clicked(gtx) {
		window.stop()
	}
	return layout.UniformInset(unit.Dp(10)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			// Row 1: connection status and detection status on one line.
			layout.Rigid(func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
					layout.Rigid(material.Body1(window.theme, model.ConnectionText).Layout),
					layout.Rigid(layout.Spacer{Width: unit.Dp(16)}.Layout),
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						label := material.Body1(window.theme, model.StateText)
						if model.Critical {
							label.Color = colorAlert
						}
						return label.Layout(gtx)
					}),
				)
			}),
			layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
			// Row 2: compact start/stop buttons on one line.
			layout.Rigid(func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						return smallButton(gtx, window.theme, &window.startButton, "开始监控")
					}),
					layout.Rigid(layout.Spacer{Width: unit.Dp(8)}.Layout),
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						return smallButton(gtx, window.theme, &window.stopButton, "停止监控")
					}),
				)
			}),
			layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
			// Row 3: event text and the red-note on one line.
			layout.Rigid(func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
					layout.Rigid(material.Body1(window.theme, model.EventText).Layout),
					layout.Rigid(layout.Spacer{Width: unit.Dp(12)}.Layout),
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						note := material.Body2(window.theme, "红色=确认摔倒")
						note.Color = colorSubtle
						return note.Layout(gtx)
					}),
				)
			}),
			layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
			layout.Rigid(material.Body2(window.theme, "最近确认截图（双击看原图）").Layout),
			layout.Rigid(layout.Spacer{Height: unit.Dp(4)}.Layout),
			// Remaining area: 3x3 reverse-chronological screenshot gallery.
			layout.Flexed(1, window.layoutGallery),
		)
	})
}

func smallButton(gtx layout.Context, theme *material.Theme, click *widget.Clickable, label string) layout.Dimensions {
	button := material.Button(theme, click, label)
	button.Inset = layout.Inset{Top: unit.Dp(4), Bottom: unit.Dp(4), Left: unit.Dp(10), Right: unit.Dp(10)}
	button.TextSize = unit.Sp(13)
	return button.Layout(gtx)
}

func (window *Window) layoutGallery(gtx layout.Context) layout.Dimensions {
	rows := make([]layout.FlexChild, 0, 3)
	for r := 0; r < 3; r++ {
		r := r
		rows = append(rows, layout.Flexed(1, func(gtx layout.Context) layout.Dimensions {
			cols := make([]layout.FlexChild, 0, 3)
			for c := 0; c < 3; c++ {
				index := r*3 + c
				cols = append(cols, layout.Flexed(1, func(gtx layout.Context) layout.Dimensions {
					if index < len(window.gallery) {
						return window.layoutCell(gtx, window.gallery[index])
					}
					return layout.Dimensions{Size: gtx.Constraints.Min}
				}))
			}
			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx, cols...)
		}))
	}
	return layout.Flex{Axis: layout.Vertical}.Layout(gtx, rows...)
}

func (window *Window) layoutCell(gtx layout.Context, item *galleryItem) layout.Dimensions {
	return item.click.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
		return layout.UniformInset(unit.Dp(3)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
			return widget.Image{Src: item.op, Fit: widget.Contain, Position: layout.Center}.Layout(gtx)
		})
	})
}

func (window *Window) layoutViewer(gtx layout.Context) layout.Dimensions {
	item := window.viewing
	if item == nil {
		return layout.Dimensions{Size: gtx.Constraints.Min}
	}
	return layout.UniformInset(unit.Dp(24)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			layout.Rigid(func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						caption := material.Body1(window.theme, item.caption)
						caption.Color = colorSurface
						return caption.Layout(gtx)
					}),
					layout.Flexed(1, layout.Spacer{}.Layout),
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						return smallButton(gtx, window.theme, &window.viewerClose, "关闭")
					}),
				)
			}),
			layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
			layout.Flexed(1, func(gtx layout.Context) layout.Dimensions {
				return layout.Center.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
					return widget.Image{Src: item.op, Fit: widget.Contain, Position: layout.Center}.Layout(gtx)
				})
			}),
		)
	})
}

func (window *Window) layoutDialog(gtx layout.Context, record alert.Record) layout.Dimensions {
	width := gtx.Dp(420)
	if width > gtx.Constraints.Max.X {
		width = gtx.Constraints.Max.X
	}
	gtx.Constraints.Min.X = width
	gtx.Constraints.Max.X = width
	return layout.Stack{}.Layout(gtx,
		layout.Expanded(func(gtx layout.Context) layout.Dimensions {
			rect := image.Rectangle{Max: gtx.Constraints.Min}
			paint.FillShape(gtx.Ops, colorSurface, clip.UniformRRect(rect, gtx.Dp(8)).Op(gtx.Ops))
			return layout.Dimensions{Size: gtx.Constraints.Min}
		}),
		layout.Stacked(func(gtx layout.Context) layout.Dimensions {
			return layout.UniformInset(unit.Dp(16)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
				return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
					layout.Rigid(func(gtx layout.Context) layout.Dimensions {
						title := material.H6(window.theme, "确认摔倒")
						title.Color = colorAlert
						return title.Layout(gtx)
					}),
					layout.Rigid(material.Body1(window.theme, "人员："+record.Event.TrackID).Layout),
					layout.Rigid(material.Body1(window.theme, fmt.Sprintf("延迟：%.2f 秒", record.Event.LatencySeconds)).Layout),
					layout.Rigid(material.Body2(window.theme, "截图："+record.ScreenshotPath).Layout),
					layout.Rigid(layout.Spacer{Height: unit.Dp(8)}.Layout),
					layout.Rigid(material.Button(window.theme, &window.ackButton, "我已知晓").Layout),
				)
			})
		}),
	)
}

func (window *Window) layoutSettings(gtx layout.Context, model ViewModel) layout.Dimensions {
	return layout.UniformInset(unit.Dp(12)).Layout(gtx, func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			layout.Rigid(material.H6(window.theme, "来源与运行依赖（只读，不显示 RTSP 地址或密码）").Layout),
			layout.Rigid(material.Body1(window.theme, model.SettingsSummary).Layout),
			layout.Rigid(material.Body1(window.theme, "模型 SHA-256："+shortHash(window.settings.ModelSHA256)).Layout),
			layout.Rigid(material.Body1(window.theme, "运行依赖："+window.settings.RuntimeSummary).Layout),
			layout.Rigid(material.Body1(window.theme, "事件参数："+window.settings.EventSummary).Layout),
			layout.Rigid(material.Body2(window.theme, "参数在配置文件中维护；修改后请停止并重新开始监控。").Layout),
		)
	})
}

func highestState(result fall.FrameResult) fall.State {
	state := fall.Normal
	for _, person := range result.People {
		switch person.State {
		case fall.Confirmed:
			return fall.Confirmed
		case fall.Suspect:
			if state == fall.Normal || state == fall.Recovering {
				state = fall.Suspect
			}
		case fall.Recovering:
			if state == fall.Normal {
				state = fall.Recovering
			}
		}
	}
	return state
}

func shortHash(value string) string {
	if len(value) <= 12 {
		return value
	}
	return strings.ToLower(value[:12]) + "…"
}