package main

import (
    "fmt"
    "math/rand"
    "time"
    tui "github.com/grindlemire/go-tui"
)

type dashboardApp struct {
    cpu         *tui.State[int]
    mem         *tui.State[int]
    disk        *tui.State[int]
    netIn       *tui.State[int]
    netOut      *tui.State[int]
    sparkIn     *tui.State[[]int]
    sparkOut    *tui.State[[]int]
    events      *tui.State[[]string]
    eventCh     <-chan string
    scrollY     *tui.State[int]
    eventsRef   *tui.Ref
}

func Dashboard(eventCh <-chan string) *dashboardApp {
    return &dashboardApp{
        cpu:        tui.NewState(45),
        mem:        tui.NewState(62),
        disk:       tui.NewState(38),
        netIn:      tui.NewState(142),
        netOut:     tui.NewState(89),
        sparkIn:    tui.NewState([]int{3, 5, 4, 6, 7, 5, 4, 3, 5, 6, 7, 8, 6, 5, 4, 3, 5, 6, 7, 5}),
        sparkOut:   tui.NewState([]int{2, 3, 4, 3, 5, 4, 3, 2, 3, 4, 5, 6, 4, 3, 2, 3, 4, 5, 4, 3}),
        events:     tui.NewState([]string{}),
        eventCh:    eventCh,
        scrollY:    tui.NewState(0),
        eventsRef:  tui.NewRef(),
    }
}

func (d *dashboardApp) scrollBy(delta int) {
    el := d.eventsRef.El()
    if el == nil {
        return
    }

    _, maxY := el.MaxScroll()
    newY := d.scrollY.Get() + delta
    if newY < 0 {
        newY = 0
    } else if newY > maxY {
        newY = maxY
    }
    d.scrollY.Set(newY)
}

func (d *dashboardApp) KeyMap() tui.KeyMap {
    return tui.KeyMap{
        tui.On(tui.KeyEscape, func(ke tui.KeyEvent) { ke.App().Stop() }),
        tui.On(tui.Rune('q'), func(ke tui.KeyEvent) { ke.App().Stop() }),
        tui.On(tui.Rune('j'), func(ke tui.KeyEvent) { d.scrollBy(1) }),
        tui.On(tui.Rune('k'), func(ke tui.KeyEvent) { d.scrollBy(-1) }),
        tui.On(tui.KeyDown, func(ke tui.KeyEvent) { d.scrollBy(1) }),
        tui.On(tui.KeyUp, func(ke tui.KeyEvent) { d.scrollBy(-1) }),
    }
}

func (d *dashboardApp) HandleMouse(me tui.MouseEvent) bool {
    switch me.Button {
    case tui.MouseWheelUp:
        d.scrollBy(-1)
        return true
    case tui.MouseWheelDown:
        d.scrollBy(1)
        return true
    }
    return false
}

func (d *dashboardApp) Watchers() []tui.Watcher {
    return []tui.Watcher{
        tui.OnTimer(500*time.Millisecond, d.updateMetrics),
        tui.Watch(d.eventCh, d.addEvent),
    }
}

func (d *dashboardApp) updateMetrics() {
    d.cpu.Set(clampVal(d.cpu.Get()+rand.Intn(11)-5, 5, 95))
    d.mem.Set(clampVal(d.mem.Get()+rand.Intn(7)-3, 20, 90))
    d.disk.Set(clampVal(d.disk.Get()+rand.Intn(3)-1, 20, 80))
    d.netIn.Set(clampVal(d.netIn.Get()+rand.Intn(41)-20, 50, 300))
    d.netOut.Set(clampVal(d.netOut.Get()+rand.Intn(31)-15, 30, 200))

    inData := d.sparkIn.Get()
    inData = append(inData[1:], d.netIn.Get()/30)
    d.sparkIn.Set(inData)

    outData := d.sparkOut.Get()
    outData = append(outData[1:], d.netOut.Get()/30)
    d.sparkOut.Set(outData)
}

func (d *dashboardApp) addEvent(event string) {
    current := d.events.Get()
    ts := time.Now().Format("15:04:05")
    entry := fmt.Sprintf("%s  %s", ts, event)
    current = append(current, entry)
    if len(current) > 50 {
        current = current[len(current)-50:]
    }
    d.events.Set(current)

    // Auto-scroll to bottom
    el := d.eventsRef.El()
    if el != nil {
        _, maxY := el.MaxScroll()
        d.scrollY.Set(maxY + 1)
    }
}

func clampVal(v, min, max int) int {
    if v < min {
        return min
    }
    if v > max {
        return max
    }
    return v
}

func metricBar(value, max int) string {
    width := 20
    filled := value * width / max
    bar := ""
    for i := 0; i < width; i++ {
        if i < filled {
            bar += "█"
        } else {
            bar += "░"
        }
    }
    return bar
}

func metricColor(value int) string {
    if value >= 80 {
        return "text-red font-bold"
    }
    if value >= 60 {
        return "text-yellow"
    }
    return "text-green"
}

func sparkline(data []int) string {
    blocks := []rune{'▁', '▂', '▃', '▄', '▅', '▆', '▇', '█'}
    maxVal := 1
    for _, v := range data {
        if v > maxVal {
            maxVal = v
        }
    }
    s := ""
    for _, v := range data {
        idx := v * 7 / maxVal
        if idx > 7 {
            idx = 7
        }
        s += string(blocks[idx])
    }
    return s
}

func produceEvents(ch chan<- string, stopCh <-chan struct{}) {
    defer close(ch)
    events := []string{
        "Deploy completed",
        "Health check passed",
        "New connection from 10.0.0.5",
        "Cache invalidated",
        "Backup complete",
        "Certificate renewed",
        "Config reloaded",
        "Scale up: 3 replicas",
        "Alert cleared: cpu",
        "Metrics exported",
    }
    for {
        delay := time.Duration(2000+rand.Intn(3000)) * time.Millisecond
        select {
        case <-stopCh:
            return
        case <-time.After(delay):
        }
        event := events[rand.Intn(len(events))]
        select {
        case <-stopCh:
            return
        case ch <- event:
        }
    }
}

templ (d *dashboardApp) Render() {
    <div class="flex-col p-1 gap-1 h-full border-rounded border-cyan">
        <div class="flex justify-center shrink-0">
            <span class="text-gradient-cyan-magenta font-bold">Dashboard</span>
        </div>

        // Metric gauges
        <div class="flex gap-1 shrink-0">
            <div class="flex-col border-rounded p-1 gap-1" flexGrow={1.0}>
                <span class="text-gradient-cyan-magenta font-bold">CPU</span>
                <span class={metricColor(d.cpu.Get())}>{metricBar(d.cpu.Get(), 100)}</span>
                <span class={metricColor(d.cpu.Get()) + " font-bold"}>{fmt.Sprintf("%d%%", d.cpu.Get())}</span>
            </div>
            <div class="flex-col border-rounded p-1 gap-1" flexGrow={1.0}>
                <span class="text-gradient-cyan-magenta font-bold">Memory</span>
                <span class={metricColor(d.mem.Get())}>{metricBar(d.mem.Get(), 100)}</span>
                <span class={metricColor(d.mem.Get()) + " font-bold"}>{fmt.Sprintf("%d%%", d.mem.Get())}</span>
            </div>
            <div class="flex-col border-rounded p-1 gap-1" flexGrow={1.0}>
                <span class="text-gradient-cyan-magenta font-bold">Disk</span>
                <span class={metricColor(d.disk.Get())}>{metricBar(d.disk.Get(), 100)}</span>
                <span class={metricColor(d.disk.Get()) + " font-bold"}>{fmt.Sprintf("%d%%", d.disk.Get())}</span>
            </div>
        </div>

        // Network Traffic + Recent Events
        <div class="flex gap-1 flex-grow">
            <div class="flex-col border-rounded p-1 gap-1" flexGrow={1.0}>
                <span class="text-gradient-cyan-magenta font-bold">Network Traffic</span>
                <div class="flex gap-1">
                    <span class="font-dim">In: </span>
                    <span class="text-cyan">{sparkline(d.sparkIn.Get())}</span>
                </div>
                <div class="flex gap-1">
                    <span class="font-dim">Out:</span>
                    <span class="text-magenta">{sparkline(d.sparkOut.Get())}</span>
                </div>
                <div class="flex gap-2">
                    <span class="text-cyan font-bold">{fmt.Sprintf("In: %d MB/s", d.netIn.Get())}</span>
                    <span class="text-magenta font-bold">{fmt.Sprintf("Out: %d MB/s", d.netOut.Get())}</span>
                </div>
            </div>

            <div
                ref={d.eventsRef}
                class="flex-col border-rounded p-1 gap-1"
                flexGrow={1.0}
                scrollable={tui.ScrollVertical}
                scrollOffset={0, d.scrollY.Get()}
            >
                <span class="text-gradient-cyan-magenta font-bold">Recent Events</span>
                for _, event := range d.events.Get() {
                    <span class="text-green">{event}</span>
                }
                if len(d.events.Get()) == 0 {
                    <span class="font-dim">Waiting for events...</span>
                }
            </div>
        </div>

        <div class="flex justify-center shrink-0">
            <span class="font-dim">j/k scroll events | q to quit</span>
        </div>
    </div>
}