"use client";

import { BitAura } from "@/src/components/bits/BitAura";
import * as React from "react";
import { useContent } from "@/src/components/ContentProvider";
import { fill } from "@/src/domain/template";

/**
 * PipelineRun: what happens between a change and its release, shown as the test run it is.
 * A change breaks something elsewhere, the run catches it, the release is blocked, the fix
 * goes in, the release goes out. Output is illustrative, modelled on a real test runner.
 */

type Suite = {
  readonly file: string;
  readonly tests: number;
  readonly ms: number;
};

const SUITES: readonly Suite[] = [
  { file: "auth/login.spec.ts", tests: 9, ms: 412 },
  { file: "orders/create.spec.ts", tests: 12, ms: 688 },
  { file: "orders/status.spec.ts", tests: 7, ms: 301 },
  { file: "invoices/total.spec.ts", tests: 14, ms: 954 },
  { file: "emails/confirmation.spec.ts", tests: 6, ms: 377 },
  { file: "emails/invoice-mail.spec.ts", tests: 5, ms: 290 },
];

/** A change and the test it breaks elsewhere. The texts are in en.ts and de.ts, by id. */
type Scenario = {
  readonly id: string;
  readonly branch: string;
  readonly failingFile: string;
};

const SCENARIOS: readonly Scenario[] = [
  {
    id: "orders",
    branch: "change/order-discounts",
    failingFile: "invoices/total.spec.ts",
  },
  {
    id: "login",
    branch: "change/login-with-username",
    failingFile: "emails/confirmation.spec.ts",
  },
  {
    id: "invoices",
    branch: "change/invoice-layout",
    failingFile: "emails/invoice-mail.spec.ts",
  },
  {
    id: "emails",
    branch: "change/email-queue",
    failingFile: "orders/status.spec.ts",
  },
];

const STAGE_COUNT = 4;
const TOTAL_TESTS = SUITES.reduce((sum, suite) => sum + suite.tests, 0);

/**
 * The run as a sequence of frames. Each frame says how far the first attempt got,
 * and whether the fix has been pushed and how far the second attempt got.
 */
type Frame = {
  readonly attempt: 1 | 2;
  /** Stages finished so far (0..4). */
  readonly stagesDone: number;
  /** Suites reported so far within the Tests stage. */
  readonly suitesDone: number;
};

const buildFrames = (): readonly Frame[] => {
  const frames: Frame[] = [];
  for (const attempt of [1, 2] as const) {
    frames.push({ attempt, stagesDone: 0, suitesDone: 0 });
    frames.push({ attempt, stagesDone: 1, suitesDone: 0 });
    frames.push({ attempt, stagesDone: 2, suitesDone: 0 });
    for (let s = 1; s <= SUITES.length; s++) {
      frames.push({ attempt, stagesDone: 2, suitesDone: s });
    }
    frames.push({ attempt, stagesDone: 3, suitesDone: SUITES.length });
    frames.push({ attempt, stagesDone: 4, suitesDone: SUITES.length });
  }
  return frames;
};

const FRAMES = buildFrames();
const FRAME_MS = 420;
const HOLD_AFTER_FAIL_MS = 3200;
const FIRST_ATTEMPT_END = FRAMES.findIndex((f) => f.attempt === 2) - 1;

type StageState = "waiting" | "running" | "passed" | "failed" | "blocked";

const STAGE_STYLE: Readonly<Record<StageState, string>> = {
  waiting: "border-slate-700 text-slate-500",
  running: "border-slate-400 text-white",
  passed: "border-emerald-500/60 text-emerald-400",
  failed: "border-rose-500/70 text-rose-400",
  blocked: "border-slate-700 text-slate-500 line-through",
};

const STAGE_MARK: Readonly<Record<StageState, string>> = {
  waiting: "·",
  running: "…",
  passed: "✓",
  failed: "✕",
  blocked: "—",
};

const MONO = "font-mono text-[11px] uppercase tracking-[0.2em]";

export const PipelineRun: React.FC = () => {
  const copy = useContent().technology.pipeline;
  const [scenarioId, setScenarioId] = React.useState(SCENARIOS[0]?.id ?? "");
  const [frameIndex, setFrameIndex] = React.useState(0);
  const [run, setRun] = React.useState(0);
  const ref = React.useRef<HTMLDivElement>(null);
  const [inView, setInView] = React.useState(false);

  const scenario =
    SCENARIOS.find((item) => item.id === scenarioId) ?? SCENARIOS[0];

  React.useEffect(() => {
    const node = ref.current;
    if (!node) return;
    const observer = new IntersectionObserver(
      ([entry]) => setInView(entry?.isIntersecting ?? false),
      { threshold: 0.25 },
    );
    observer.observe(node);
    return () => observer.disconnect();
  }, []);

  React.useEffect(() => {
    if (!inView) return;
    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
      setFrameIndex(FRAMES.length - 1);
      return;
    }
    setFrameIndex(0);
    let index = 0;
    let timer = 0;
    const tick = () => {
      index += 1;
      if (index >= FRAMES.length) return;
      setFrameIndex(index);
      // Stay on the blocked release long enough to read the failure.
      const delay = index === FIRST_ATTEMPT_END ? HOLD_AFTER_FAIL_MS : FRAME_MS;
      timer = window.setTimeout(tick, delay);
    };
    timer = window.setTimeout(tick, FRAME_MS);
    return () => window.clearTimeout(timer);
  }, [inView, scenarioId, run]);

  const scenarioCopy = scenario ? copy.scenarios[scenario.id] : undefined;
  if (!scenario || !scenarioCopy) return null;

  const frame = FRAMES[frameIndex] ?? FRAMES[0];
  if (!frame) return null;

  const firstAttempt = frame.attempt === 1;
  const failingIndex = SUITES.findIndex((s) => s.file === scenario.failingFile);
  const failureSeen = firstAttempt && frame.suitesDone > failingIndex;
  const finished = frame.stagesDone === STAGE_COUNT;

  const stageState = (index: number): StageState => {
    if (index === 2 && firstAttempt && failureSeen && frame.stagesDone >= 3) {
      return "failed";
    }
    if (index === 3 && firstAttempt && frame.stagesDone >= 3 && failureSeen) {
      return finished ? "blocked" : "waiting";
    }
    if (index < frame.stagesDone) return "passed";
    if (index === frame.stagesDone) return "running";
    return "waiting";
  };

  const failedCount = failureSeen ? 1 : 0;
  const reportedTests = SUITES.slice(0, frame.suitesDone).reduce(
    (sum, suite) => sum + suite.tests,
    0,
  );

  // Which of the three explanations applies right now.
  const explain = firstAttempt ? (finished ? 1 : 0) : finished ? 2 : 1;

  const explanations = copy.explanations.map((item) => ({
    title: item.title,
    text: fill(item.text, { area: scenarioCopy.label }),
  }));

  return (
    <div
      ref={ref}
      className="grid grid-cols-1 gap-10 md:grid-cols-12 md:gap-12"
    >
      <div className="md:col-span-4">
        <p className={`${MONO} m-0 text-slate-500`}>{copy.simulate}</p>
        <div className="mt-4 flex flex-wrap gap-2">
          {SCENARIOS.map((item) => {
            const selected = item.id === scenario.id;
            return (
              <button
                key={item.id}
                type="button"
                aria-pressed={selected}
                onClick={() => {
                  setScenarioId(item.id);
                  setRun((n) => n + 1);
                }}
                className={`rounded-full border px-4 py-2 font-mono text-[11px] uppercase tracking-[0.15em] transition-colors duration-200 ${
                  selected
                    ? "border-slate-900 bg-slate-900 text-white"
                    : "border-slate-200 bg-white text-slate-600 hover:border-slate-400 hover:text-slate-900"
                }`}
              >
                {copy.scenarios[item.id]?.label}
              </button>
            );
          })}
        </div>

        <ol className="m-0 mt-10 list-none p-0" aria-live="polite">
          {explanations.map((item, index) => {
            const active = index === explain;
            return (
              <li
                key={item.title}
                className={`border-t py-5 transition-colors duration-300 ${
                  active ? "border-slate-900" : "border-slate-200"
                }`}
              >
                <p
                  className={`m-0 font-sans text-lg font-bold tracking-tight transition-colors duration-300 md:text-xl ${
                    active ? "text-slate-900" : "text-slate-400"
                  }`}
                >
                  {item.title}
                </p>
                <p
                  className={`m-0 mt-2 font-sans text-base leading-relaxed transition-colors duration-300 ${
                    // On phones only the current step is spelled out.
                    active
                      ? "block text-slate-600"
                      : "hidden text-slate-400 md:block"
                  }`}
                >
                  {item.text}
                </p>
              </li>
            );
          })}
        </ol>

        <button
          type="button"
          onClick={() => setRun((n) => n + 1)}
          className="mt-6 rounded-full border border-slate-200 bg-white px-4 py-2 font-mono text-[11px] uppercase tracking-[0.15em] text-slate-600 transition-colors hover:border-slate-400 hover:text-slate-900"
        >
          {copy.runAgain}
        </button>
      </div>

      <div className="md:col-span-8">
        <BitAura source="right" tone="light">
          <div className="overflow-hidden rounded-3xl bg-slate-900 font-mono text-[12px] leading-relaxed text-slate-300 md:text-[13px]">
            {/* Run header */}
            <div className="flex flex-wrap items-center justify-between gap-3 border-b border-slate-800 px-5 py-4 md:px-7">
              <div className="flex items-center gap-3">
                <span className="flex gap-1.5" aria-hidden="true">
                  <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
                  <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
                  <span className="h-2.5 w-2.5 rounded-full bg-slate-700" />
                </span>
                <span className="text-slate-400">
                  {scenario.branch}
                  <span className="text-slate-600"> → </span>main
                </span>
              </div>
              <span className="text-slate-500">
                {copy.run} #{frame.attempt === 1 ? 481 : 482}
                {frame.attempt === 2 && (
                  <span className="text-slate-400"> · {copy.fixPushed}</span>
                )}
              </span>
            </div>

            {/* Stages */}
            <div className="grid grid-cols-2 gap-2 border-b border-slate-800 px-5 py-4 sm:grid-cols-4 md:px-7">
              {copy.stages.map((stage, index) => {
                const state = stageState(index);
                return (
                  <div
                    key={stage}
                    className={`flex items-center justify-between rounded-xl border px-3 py-2.5 transition-colors duration-200 ${STAGE_STYLE[state]}`}
                  >
                    <span>{stage}</span>
                    <span aria-hidden="true">{STAGE_MARK[state]}</span>
                  </div>
                );
              })}
            </div>

            {/* Test output */}
            <div className="min-h-[21rem] px-5 py-5 md:px-7 md:py-6">
              {frame.stagesDone < 2 && (
                <p className="m-0 text-[12px] leading-relaxed text-slate-500 md:text-[13px]">
                  {frame.stagesDone === 0 ? copy.lint : copy.types}
                </p>
              )}
              {SUITES.slice(0, frame.suitesDone).map((suite, index) => {
                const failed = firstAttempt && index === failingIndex;
                return (
                  <div key={suite.file}>
                    <div className="flex items-baseline gap-3">
                      <span
                        className={`w-10 shrink-0 font-bold ${failed ? "text-rose-400" : "text-emerald-400"}`}
                      >
                        {failed ? "FAIL" : "PASS"}
                      </span>
                      <span className="min-w-0 flex-1 truncate text-slate-200">
                        {suite.file}
                      </span>
                      <span className="hidden text-slate-500 sm:inline">
                        {suite.tests} {copy.tests}
                      </span>
                      <span className="w-14 shrink-0 text-right text-slate-600">
                        {suite.ms} ms
                      </span>
                    </div>
                    {failed && (
                      <div className="my-2 ml-[3.25rem] border-l border-rose-500/50 pl-4">
                        <p className="m-0 text-[12px] leading-relaxed text-slate-200 md:text-[13px]">
                          ● {scenarioCopy.testName}
                        </p>
                        <p className="m-0 text-[12px] leading-relaxed text-emerald-400 md:text-[13px]">
                          {copy.expected}&nbsp; {scenarioCopy.expected}
                        </p>
                        <p className="m-0 text-[12px] leading-relaxed text-rose-400 md:text-[13px]">
                          {copy.received}&nbsp; {scenarioCopy.received}
                        </p>
                      </div>
                    )}
                  </div>
                );
              })}
              {frame.stagesDone === 2 && frame.suitesDone < SUITES.length && (
                <p className="m-0 text-[12px] leading-relaxed text-slate-500 md:text-[13px]">
                  {fill(copy.runningFile, {
                    file: SUITES[frame.suitesDone]?.file ?? "",
                  })}
                </p>
              )}
            </div>

            {/* Summary */}
            <div className="flex flex-wrap items-center justify-between gap-3 border-t border-slate-800 px-5 py-4 md:px-7">
              <span>
                <span className="text-slate-500">{copy.summaryLabel} </span>
                {failedCount > 0 && (
                  <span className="text-rose-400">
                    {fill(copy.failed, { n: failedCount })},{" "}
                  </span>
                )}
                <span className="text-emerald-400">
                  {fill(copy.passed, { n: reportedTests - failedCount })}
                </span>
                <span className="text-slate-500">
                  {" "}
                  {fill(copy.of, { total: TOTAL_TESTS })}
                </span>
              </span>
              <span
                className={`rounded-full px-3 py-1 font-bold uppercase tracking-[0.15em] ${
                  !finished
                    ? "bg-slate-800 text-slate-400"
                    : firstAttempt
                      ? "bg-rose-500/15 text-rose-400"
                      : "bg-emerald-500/15 text-emerald-400"
                }`}
              >
                {!finished
                  ? copy.pending
                  : firstAttempt
                    ? copy.blocked
                    : copy.released}
              </span>
            </div>
          </div>
        </BitAura>
        <p className="m-0 mt-4 font-sans text-sm leading-relaxed text-slate-400">
          {copy.footnote}
        </p>
      </div>
    </div>
  );
};