import { apiFetch } from "./api.js";
import { dom } from "./dom.js";
import { state } from "./state.js";

function normalizeChartItem(item) {
  let valueNumber = null;
  if (typeof item?.value_number === "number" && Number.isFinite(item.value_number)) {
    valueNumber = item.value_number;
  } else if (typeof item?.value === "number" && Number.isFinite(item.value)) {
    valueNumber = item.value;
  } else if (typeof item?.value === "boolean") {
    valueNumber = item.value ? 1 : 0;
  } else if (typeof item?.value?.float === "number" && Number.isFinite(item.value.float)) {
    valueNumber = item.value.float;
  } else if (typeof item?.value?.int === "number" && Number.isFinite(item.value.int)) {
    valueNumber = item.value.int;
  } else if (typeof item?.value?.uint === "number" && Number.isFinite(item.value.uint)) {
    valueNumber = item.value.uint;
  } else if (typeof item?.value?.bool === "boolean") {
    valueNumber = item.value.bool ? 1 : 0;
  } else if (typeof item?.value_text === "string") {
    const parsed = Number(item.value_text);
    if (Number.isFinite(parsed)) {
      valueNumber = parsed;
    }
  }

  return {
    timestamp: item?.timestamp || "",
    valueNumber,
    valueText: item?.value_text || (valueNumber === null ? "" : String(valueNumber)),
  };
}

function formatAxisValue(value) {
  if (!Number.isFinite(value)) {
    return "--";
  }
  if (Math.abs(value) >= 1000 || Math.abs(value) < 0.01) {
    return value.toExponential(2);
  }
  return value.toFixed(2);
}

function formatTimeLabel(timestamp) {
  if (!timestamp) {
    return "--";
  }
  const match = String(timestamp).match(/(\d{2}:\d{2}:\d{2})/);
  return match ? match[1] : String(timestamp);
}

export async function openChart(pointId, pointName) {
  state.chartPointId = pointId;
  state.chartPointName = pointName || "点位";
  dom.chartTitle.textContent = `${state.chartPointName} 趋势图`;

  const items = await apiFetch(`/api/point/${pointId}/history?limit=120`);
  state.chartData = (items || [])
    .map(normalizeChartItem)
    .filter((item) => item.valueNumber !== null);

  renderChart();
}

export function appendChartPoint(item) {
  if (!state.chartPointId) {
    return;
  }

  const normalized = normalizeChartItem(item);
  if (normalized.valueNumber === null) {
    return;
  }

  const last = state.chartData[state.chartData.length - 1];
  if (
    last &&
    last.timestamp === normalized.timestamp &&
    last.valueText === normalized.valueText &&
    last.valueNumber === normalized.valueNumber
  ) {
    return;
  }

  state.chartData.push(normalized);
  if (state.chartData.length > 120) {
    state.chartData = state.chartData.slice(-120);
  }
  renderChart();
}

export function renderChart() {
  const ctx = dom.chartCanvas.getContext("2d");
  const width = dom.chartCanvas.width;
  const height = dom.chartCanvas.height;
  ctx.clearRect(0, 0, width, height);

  if (!state.chartData.length) {
    ctx.fillStyle = "#94a3b8";
    ctx.font = "14px Segoe UI";
    ctx.fillText("点击点位行查看图表", 24, 40);
    dom.chartSummary.textContent = "点击点位行查看图表";
    return;
  }

  const values = state.chartData.map((item) => item.valueNumber);
  let min = Math.min(...values);
  let max = Math.max(...values);
  if (min === max) {
    min -= 1;
    max += 1;
  }

  const padding = { top: 20, right: 20, bottom: 42, left: 64 };
  const plotWidth = width - padding.left - padding.right;
  const plotHeight = height - padding.top - padding.bottom;

  ctx.strokeStyle = "#cbd5e1";
  ctx.lineWidth = 1;

  for (let i = 0; i <= 4; i += 1) {
    const y = padding.top + (plotHeight / 4) * i;
    ctx.beginPath();
    ctx.moveTo(padding.left, y);
    ctx.lineTo(width - padding.right, y);
    ctx.stroke();
  }

  ctx.beginPath();
  ctx.moveTo(padding.left, padding.top);
  ctx.lineTo(padding.left, height - padding.bottom);
  ctx.lineTo(width - padding.right, height - padding.bottom);
  ctx.strokeStyle = "#94a3b8";
  ctx.stroke();

  ctx.fillStyle = "#64748b";
  ctx.font = "12px Segoe UI";
  for (let i = 0; i <= 4; i += 1) {
    const value = max - ((max - min) / 4) * i;
    const y = padding.top + (plotHeight / 4) * i;
    ctx.fillText(formatAxisValue(value), 8, y + 4);
  }

  const firstLabel = formatTimeLabel(state.chartData[0]?.timestamp);
  const middleLabel = formatTimeLabel(
    state.chartData[Math.floor((state.chartData.length - 1) / 2)]?.timestamp,
  );
  const lastLabel = formatTimeLabel(state.chartData[state.chartData.length - 1]?.timestamp);

  ctx.fillText(firstLabel, padding.left, height - 12);
  const middleWidth = ctx.measureText(middleLabel).width;
  ctx.fillText(middleLabel, padding.left + plotWidth / 2 - middleWidth / 2, height - 12);
  const lastWidth = ctx.measureText(lastLabel).width;
  ctx.fillText(lastLabel, width - padding.right - lastWidth, height - 12);

  ctx.save();
  ctx.translate(16, padding.top + plotHeight / 2);
  ctx.rotate(-Math.PI / 2);
  ctx.fillStyle = "#64748b";
  ctx.fillText("数值", 0, 0);
  ctx.restore();
  ctx.fillText("时间", width / 2 - 12, height - 28);

  ctx.strokeStyle = "#2563eb";
  ctx.lineWidth = 2;
  ctx.beginPath();

  state.chartData.forEach((item, index) => {
    const x = padding.left + (plotWidth * index) / Math.max(1, state.chartData.length - 1);
    const y = padding.top + ((max - item.valueNumber) / (max - min)) * plotHeight;
    if (index === 0) {
      ctx.moveTo(x, y);
    } else {
      ctx.lineTo(x, y);
    }
  });

  ctx.stroke();

  const latest = state.chartData[state.chartData.length - 1];
  dom.chartSummary.textContent = `Latest ${state.chartData.length} points, current value ${latest.valueText || latest.valueNumber}`;
}