// Config-timeline chart: plots Preseem QoE (latency, throughput, loss)
// over time and overlays vertical markers for each config change event,
// so an operator can spot whether a metric regression coincides with a
// device config edit.
//
// Lazy-loaded; reuses Chart.js with the sensor chart (esbuild factors
// the shared Chart vendor blob into a common chunk).

import Chart from "../../vendor/chart"

interface QoePoint {
  t: string
  latency: number | null
  throughput: number | null
  loss: number | null
}

interface ChangeEvent {
  id: string
  t: string
  sections: string[]
  size: number
}

interface CheckPoint {
  t: string
  status: string
}

export const ConfigTimelineChart = {
  chart: null as any,

  mounted(this: any) {
    this.render()
  },

  updated(this: any) {
    if (this.chart) {
      this.chart.destroy()
      this.chart = null
    }
    this.render()
  },

  destroyed(this: any) {
    if (this.chart) {
      this.chart.destroy()
      this.chart = null
    }
  },

  render(this: any) {
    if (!this.el) return

    const qoe: QoePoint[] = parseJSON(this.el.dataset.qoe)
    const changes: ChangeEvent[] = parseJSON(this.el.dataset.changes)
    const checks: CheckPoint[] = parseJSON(this.el.dataset.checks)

    // Replace the loading placeholder with a fresh canvas every render.
    this.el.innerHTML = ""
    const canvas = document.createElement("canvas")
    this.el.appendChild(canvas)

    if (qoe.length === 0 && checks.length === 0) {
      const empty = document.createElement("div")
      empty.className = "flex items-center justify-center h-full text-base-content/40 text-sm"
      empty.textContent = "No metrics in this period."
      this.el.innerHTML = ""
      this.el.appendChild(empty)
      return
    }

    const ctx = canvas.getContext("2d")
    if (!ctx) return

    const datasets: any[] = []
    if (qoe.some((p) => p.latency != null)) {
      datasets.push({
        label: "Latency (ms)",
        yAxisID: "y_latency",
        borderColor: "rgb(59, 130, 246)",
        backgroundColor: "rgba(59, 130, 246, 0.15)",
        data: qoe.map((p) => ({ x: Date.parse(p.t), y: p.latency })),
        borderWidth: 2,
        tension: 0.35,
        pointRadius: 0,
        pointHoverRadius: 3,
        spanGaps: true,
      })
    }
    if (qoe.some((p) => p.throughput != null)) {
      datasets.push({
        label: "Throughput (Mbps)",
        yAxisID: "y_throughput",
        borderColor: "rgb(34, 197, 94)",
        backgroundColor: "rgba(34, 197, 94, 0.15)",
        data: qoe.map((p) => ({ x: Date.parse(p.t), y: p.throughput })),
        borderWidth: 2,
        tension: 0.35,
        pointRadius: 0,
        pointHoverRadius: 3,
        spanGaps: true,
      })
    }
    if (qoe.some((p) => p.loss != null)) {
      datasets.push({
        label: "Loss (%)",
        yAxisID: "y_loss",
        borderColor: "rgb(239, 68, 68)",
        backgroundColor: "rgba(239, 68, 68, 0.15)",
        data: qoe.map((p) => ({ x: Date.parse(p.t), y: p.loss })),
        borderWidth: 2,
        tension: 0.35,
        pointRadius: 0,
        pointHoverRadius: 3,
        spanGaps: true,
      })
    }

    // Failed checks rendered as scatter points pinned along the x-axis,
    // separate dataset so the legend can toggle them off.
    const failedChecks = checks.filter((c) => c.status === "failed" || c.status === "down")
    if (failedChecks.length > 0) {
      datasets.push({
        label: "Check failed",
        yAxisID: "y_event",
        type: "scatter" as const,
        borderColor: "rgb(220, 38, 38)",
        backgroundColor: "rgb(220, 38, 38)",
        data: failedChecks.map((c) => ({ x: Date.parse(c.t), y: 0 })),
        pointStyle: "triangle",
        pointRadius: 5,
        pointHoverRadius: 7,
        showLine: false,
      })
    }

    const isDark = document.documentElement.getAttribute("data-theme") === "dark"
    const gridColor = isDark ? "rgba(255,255,255,0.08)" : "rgba(0,0,0,0.06)"
    const labelColor = isDark ? "#cbd5e1" : "#475569"
    const changeMarkerColor = isDark ? "rgba(168, 85, 247, 0.85)" : "rgba(124, 58, 237, 0.85)"

    // Custom plugin: draw a vertical dashed line at each config change
    // timestamp, with a small badge showing how many sections changed.
    const changeMarkerPlugin = {
      id: "configChangeMarkers",
      afterDatasetsDraw(chart: any) {
        const xScale = chart.scales.x
        const { chartArea, ctx } = chart
        if (!xScale || !chartArea) return

        ctx.save()
        ctx.strokeStyle = changeMarkerColor
        ctx.lineWidth = 1.5
        ctx.setLineDash([4, 4])
        ctx.font = "10px ui-sans-serif, system-ui, sans-serif"
        ctx.fillStyle = changeMarkerColor
        ctx.textAlign = "center"
        ctx.textBaseline = "top"

        for (const change of changes) {
          const tMs = Date.parse(change.t)
          if (Number.isNaN(tMs)) continue
          const x = xScale.getPixelForValue(tMs)
          if (x < chartArea.left || x > chartArea.right) continue

          ctx.beginPath()
          ctx.moveTo(x, chartArea.top)
          ctx.lineTo(x, chartArea.bottom)
          ctx.stroke()

          const label = `Δ ${change.size}`
          const padding = 4
          const metrics = ctx.measureText(label)
          const w = metrics.width + padding * 2
          ctx.fillStyle = changeMarkerColor
          ctx.fillRect(x - w / 2, chartArea.top - 18, w, 14)
          ctx.fillStyle = "#fff"
          ctx.fillText(label, x, chartArea.top - 16)
        }
        ctx.restore()
      },
    }

    this.chart = new Chart(ctx, {
      type: "line",
      data: { datasets },
      plugins: [changeMarkerPlugin],
      options: {
        responsive: true,
        maintainAspectRatio: false,
        animation: false,
        layout: { padding: { top: 20 } },
        interaction: { mode: "index", intersect: false },
        plugins: {
          legend: {
            position: "bottom",
            labels: { usePointStyle: true, padding: 12, color: labelColor },
          },
          tooltip: {
            callbacks: {
              title: (items: any) => {
                const t = items[0]?.parsed?.x
                return t ? new Date(t).toLocaleString() : ""
              },
              label: (item: any) => {
                if (item.dataset.label === "Check failed") return "Check failed"
                if (item.parsed.y == null) return `${item.dataset.label}: —`
                return `${item.dataset.label}: ${item.parsed.y.toFixed(2)}`
              },
            },
          },
        },
        scales: {
          x: {
            type: "linear",
            ticks: {
              color: labelColor,
              callback: (v: number) => new Date(v).toLocaleString([], { month: "short", day: "numeric", hour: "2-digit", minute: "2-digit" }),
              maxTicksLimit: 8,
            },
            grid: { color: gridColor },
          },
          y_latency: {
            position: "left" as const,
            display: datasets.some((d: any) => d.yAxisID === "y_latency"),
            title: { display: true, text: "ms", color: labelColor },
            ticks: { color: labelColor },
            grid: { color: gridColor },
          },
          y_throughput: {
            position: "right" as const,
            display: datasets.some((d: any) => d.yAxisID === "y_throughput"),
            title: { display: true, text: "Mbps", color: labelColor },
            ticks: { color: labelColor },
            grid: { drawOnChartArea: false },
          },
          y_loss: {
            position: "right" as const,
            display: datasets.some((d: any) => d.yAxisID === "y_loss"),
            title: { display: true, text: "%", color: labelColor },
            ticks: { color: labelColor },
            grid: { drawOnChartArea: false },
            min: 0,
          },
          y_event: {
            position: "left" as const,
            display: false,
            min: -0.5,
            max: 0.5,
          },
        },
      },
    })
  },
}

function parseJSON<T>(raw: string | undefined): T[] {
  if (!raw) return []
  try {
    const v = JSON.parse(raw)
    return Array.isArray(v) ? v : []
  } catch {
    return []
  }
}