import fs from "node:fs";
import path from "node:path";
import { execFileSync } from "node:child_process";
import { fileURLToPath } from "node:url";

const zeroShaPattern = /^0{40}$/;

const scriptDir = path.dirname(fileURLToPath(import.meta.url));

export const repoRoot = path.resolve(scriptDir, "../..");
export const artifactsDir = path.join(repoRoot, ".artifacts", "harness");
export const pnpmBin = process.platform === "win32" ? "pnpm.cmd" : "pnpm";

export const suiteDefinitions = {
  static: {
    description: "Fast static validation: lint and workspace typecheck.",
    commands: [
      { args: ["lint"], label: "Lint repository" },
      { args: ["typecheck"], label: "Typecheck workspace" }
    ]
  },
  component: {
    description: "Fast component feedback: lint, typecheck, and unit coverage.",
    commands: [
      { args: ["lint"], label: "Lint repository" },
      { args: ["typecheck"], label: "Typecheck workspace" },
      { args: ["test"], label: "Run component tests" }
    ]
  },
  docs: {
    description: "Build the Storybook review surface.",
    commands: [{ args: ["build:docs"], label: "Build Storybook" }]
  },
  a11y: {
    description: "Run Storybook accessibility validation and report violations/incomplete results.",
    commands: [{ args: ["test:e2e:a11y"], label: "Run Storybook accessibility checks" }]
  },
  "docs-smoke": {
    description: "Exercise high-value Storybook flows with Playwright.",
    commands: [{ args: ["test:e2e:smoke"], label: "Run Storybook smoke tests" }]
  },
  consumers: {
    description: "Validate generated registry metadata and downstream consumers.",
    commands: [
      { args: ["registry:check"], label: "Check registry metadata" },
      { args: ["test:registry:consumer"], label: "Run registry consumer smoke test" },
      { args: ["test:package:consumer"], label: "Run package consumer smoke test" }
    ]
  },
  pr: {
    description: "Baseline pull request gate for source, docs, and consumer surfaces.",
    commands: [
      { args: ["lint"], label: "Lint repository" },
      { args: ["typecheck"], label: "Typecheck workspace" },
      { args: ["test"], label: "Run component tests" },
      { args: ["build"], label: "Build packages" },
      { args: ["build:docs"], label: "Build Storybook" },
      { args: ["test:e2e:a11y"], label: "Run Storybook accessibility checks" },
      { args: ["registry:check"], label: "Check registry metadata" },
      { args: ["test:registry:consumer"], label: "Run registry consumer smoke test" },
      { args: ["test:package:consumer"], label: "Run package consumer smoke test" }
    ]
  },
  release: {
    description: "Full release gate, including browser-driven Storybook coverage.",
    commands: [
      { args: ["lint"], label: "Lint repository" },
      { args: ["typecheck"], label: "Typecheck workspace" },
      { args: ["test"], label: "Run component tests" },
      { args: ["build"], label: "Build packages" },
      { args: ["build:docs"], label: "Build Storybook" },
      { args: ["test:e2e:a11y"], label: "Run Storybook accessibility checks" },
      { args: ["registry:check"], label: "Check registry metadata" },
      { args: ["test:registry:consumer"], label: "Run registry consumer smoke test" },
      { args: ["test:package:consumer"], label: "Run package consumer smoke test" },
      { args: ["test:e2e:smoke"], label: "Run Storybook smoke tests" }
    ]
  }
};

const suiteOrder = [
  "static",
  "component",
  "docs",
  "a11y",
  "docs-smoke",
  "consumers",
  "pr",
  "release"
];

const prSupersededSuites = ["static", "component", "docs", "a11y", "docs-smoke", "consumers"];
const releaseSupersededSuites = [...prSupersededSuites, "pr"];

const rootStaticFiles = new Set([
  "eslint.config.mjs",
  "package.json",
  "playwright.config.ts",
  "pnpm-lock.yaml",
  "pnpm-workspace.yaml",
  "tsconfig.base.json",
  "tsconfig.json",
  "vitest.config.ts"
]);

function normalizeFilePath(filePath) {
  return filePath.replace(/\\/g, path.posix.sep).split(path.sep).join(path.posix.sep);
}

function isExactMatch(filePath, exactPaths) {
  return exactPaths.has(filePath);
}

function isWithin(filePath, directory) {
  return filePath === directory || filePath.startsWith(`${directory}/`);
}

function isPackageSourceChange(filePath) {
  return isWithin(filePath, "packages/ui/src") || isWithin(filePath, "packages/tokens/src");
}

function isPackageContractChange(filePath) {
  return (
    isPackageSourceChange(filePath) ||
    filePath === "packages/ui/package.json" ||
    filePath === "packages/tokens/package.json"
  );
}

function isDocsSurfaceChange(filePath) {
  return isWithin(filePath, "apps/docs") || isWithin(filePath, ".storybook");
}

function isDocsInteractiveChange(filePath) {
  return (
    isWithin(filePath, "apps/docs/src") ||
    isWithin(filePath, ".storybook") ||
    filePath === "playwright.config.ts"
  );
}

function isConsumerSurfaceChange(filePath) {
  return (
    isWithin(filePath, "registry") ||
    isWithin(filePath, "tests/package-consumer") ||
    isWithin(filePath, "tests/registry") ||
    filePath === "scripts/build-registry.mjs" ||
    filePath === "scripts/registry-install.mjs" ||
    isPackageContractChange(filePath)
  );
}

function isHarnessControlPlaneChange(filePath) {
  return (
    isWithin(filePath, "scripts/harness") ||
    filePath === "playwright.config.ts" ||
    filePath === "vitest.config.ts" ||
    isWithin(filePath, "tests/e2e/support") ||
    filePath === "AGENTS.md" ||
    filePath === "CONTRIBUTING.md" ||
    filePath === "README.md" ||
    filePath === "docs/harness-engineering.md" ||
    filePath === "docs/orchestration.md" ||
    isWithin(filePath, "docs/exec-plans")
  );
}

function isReleaseRiskChange(filePath) {
  return (
    filePath === "package.json" ||
    filePath === "docs/releasing.md" ||
    filePath === "docs/registry.md" ||
    filePath === "scripts/release-metadata.mjs" ||
    filePath === "scripts/build-registry.mjs" ||
    filePath === "scripts/registry-install.mjs" ||
    filePath === "packages/ui/package.json" ||
    filePath === "packages/tokens/package.json" ||
    isWithin(filePath, ".github/workflows") ||
    isWithin(filePath, "tests/package-consumer") ||
    isWithin(filePath, "tests/registry")
  );
}

function isStaticSurfaceChange(filePath) {
  return (
    isPackageContractChange(filePath) ||
    isDocsSurfaceChange(filePath) ||
    isWithin(filePath, "tests") ||
    isWithin(filePath, "scripts") ||
    isWithin(filePath, ".github/workflows") ||
    isExactMatch(filePath, rootStaticFiles) ||
    isHarnessControlPlaneChange(filePath) ||
    isReleaseRiskChange(filePath)
  );
}

function isLikelyCodeChange(filePath) {
  return /\.(?:cjs|css|cts|js|json|jsx|mdx|mjs|mts|scss|ts|tsx|yaml|yml)$/.test(filePath);
}

function runGitCommand(args) {
  return execFileSync("git", args, {
    cwd: repoRoot,
    encoding: "utf8"
  })
    .split("\n")
    .map((line) => line.trim())
    .filter(Boolean)
    .map((line) => normalizeFilePath(line));
}

function getWorkingTreeChangedFiles(runGitCommandFn = runGitCommand) {
  const files = new Set([
    ...runGitCommandFn(["diff", "--name-only", "--diff-filter=ACMR", "HEAD"]),
    ...runGitCommandFn(["diff", "--cached", "--name-only", "--diff-filter=ACMR", "HEAD"]),
    ...runGitCommandFn(["ls-files", "--others", "--exclude-standard"])
  ]);

  return [...files].sort();
}

export function getChangedFiles(options = {}) {
  const changedFiles = options.changedFiles ?? [];
  const from = options.from ?? null;
  const to = options.to ?? null;
  const runGitCommandFn = options.runGitCommandFn ?? runGitCommand;

  if (changedFiles.length > 0) {
    return [...new Set(changedFiles.map((filePath) => normalizeFilePath(filePath)))].sort();
  }

  if (from || to) {
    const toRef = to ?? "HEAD";

    if (from && zeroShaPattern.test(from)) {
      return [
        ...new Set([
          ...runGitCommandFn(["ls-files"]),
          ...runGitCommandFn(["ls-files", "--others", "--exclude-standard"])
        ])
      ].sort();
    }

    if (!from) {
      throw new Error("Expected --from when selecting changed files from git refs.");
    }

    return [...runGitCommandFn(["diff", "--name-only", "--diff-filter=ACMR", `${from}...${toRef}`])].sort();
  }

  return getWorkingTreeChangedFiles(runGitCommandFn);
}

function addReason(reasonMap, suiteName, filePath, reason) {
  const currentReasons = reasonMap.get(suiteName) ?? [];
  currentReasons.push({ file: filePath, reason });
  reasonMap.set(suiteName, currentReasons);
}

export function selectSuitesForChangedFiles(changedFiles) {
  const normalizedFiles = [...new Set(changedFiles.map((filePath) => normalizeFilePath(filePath)))].sort();
  const selectedSuites = new Set();
  const reasons = new Map();
  const unmatchedFiles = [];

  for (const filePath of normalizedFiles) {
    let matched = false;

    if (isReleaseRiskChange(filePath)) {
      selectedSuites.add("release");
      addReason(reasons, "release", filePath, "Release or consumer control plane changed.");
      matched = true;
    }

    if (isHarnessControlPlaneChange(filePath)) {
      selectedSuites.add("pr");
      addReason(reasons, "pr", filePath, "Harness control plane changed.");
      matched = true;
    }

    if (isPackageContractChange(filePath)) {
      selectedSuites.add("component");
      selectedSuites.add("docs");
      selectedSuites.add("a11y");
      selectedSuites.add("consumers");
      addReason(reasons, "component", filePath, "Package contract or source changed.");
      addReason(reasons, "docs", filePath, "Package changes affect the Storybook review surface.");
      addReason(reasons, "a11y", filePath, "Package changes can alter Storybook accessibility results.");
      addReason(reasons, "consumers", filePath, "Package changes affect downstream consumers.");
      matched = true;

      if (isPackageSourceChange(filePath)) {
        selectedSuites.add("docs-smoke");
        addReason(reasons, "docs-smoke", filePath, "Interactive package source changed.");
      }
    }

    if (isDocsSurfaceChange(filePath)) {
      selectedSuites.add("static");
      selectedSuites.add("docs");
      selectedSuites.add("a11y");
      addReason(reasons, "static", filePath, "Docs or Storybook source changed.");
      addReason(reasons, "docs", filePath, "Docs or Storybook source changed.");
      addReason(reasons, "a11y", filePath, "Docs or Storybook source changed.");
      matched = true;

      if (isDocsInteractiveChange(filePath)) {
        selectedSuites.add("docs-smoke");
        addReason(reasons, "docs-smoke", filePath, "Storybook stories or smoke harness changed.");
      }
    }

    if (isConsumerSurfaceChange(filePath)) {
      selectedSuites.add("static");
      selectedSuites.add("consumers");
      addReason(reasons, "static", filePath, "Registry or consumer validation surface changed.");
      addReason(reasons, "consumers", filePath, "Registry or consumer validation surface changed.");
      matched = true;
    }

    if (isStaticSurfaceChange(filePath)) {
      selectedSuites.add("static");
      addReason(reasons, "static", filePath, "Static validation surface changed.");
      matched = true;
    }

    if (!matched) {
      unmatchedFiles.push(filePath);
    }
  }

  if (selectedSuites.has("component")) {
    selectedSuites.delete("static");
    reasons.delete("static");
  }

  if (selectedSuites.has("pr")) {
    for (const suiteName of prSupersededSuites) {
      selectedSuites.delete(suiteName);
      reasons.delete(suiteName);
    }
  }

  if (selectedSuites.has("release")) {
    for (const suiteName of releaseSupersededSuites) {
      selectedSuites.delete(suiteName);
      reasons.delete(suiteName);
    }
  }

  if (selectedSuites.size === 0 && unmatchedFiles.some((filePath) => isLikelyCodeChange(filePath))) {
    selectedSuites.add("static");

    for (const filePath of unmatchedFiles) {
      if (isLikelyCodeChange(filePath)) {
        addReason(reasons, "static", filePath, "Fallback static validation for unmatched code change.");
      }
    }
  }

  return {
    changedFiles: normalizedFiles,
    reasons: Object.fromEntries(
      [...reasons.entries()].map(([suiteName, suiteReasons]) => [suiteName, suiteReasons])
    ),
    suites: suiteOrder.filter((suiteName) => selectedSuites.has(suiteName)),
    unmatchedFiles
  };
}

export function getCommandsForSuites(suiteNames) {
  const seenCommands = new Set();
  const commands = [];

  for (const suiteName of suiteNames) {
    const suite = suiteDefinitions[suiteName];

    if (!suite) {
      throw new Error(`Unknown suite "${suiteName}".`);
    }

    for (const command of suite.commands) {
      const key = command.args.join("\u0000");

      if (seenCommands.has(key)) {
        continue;
      }

      seenCommands.add(key);
      commands.push({
        ...command,
        suite: suiteName
      });
    }
  }

  return commands;
}

export function ensureKnownSuite(name) {
  if (name === "changed") {
    return;
  }

  if (!(name in suiteDefinitions)) {
    const knownSuites = [...suiteOrder, "changed"].join(", ");
    throw new Error(`Unknown suite "${name}". Expected one of: ${knownSuites}.`);
  }
}

export function writeHarnessArtifact(name, payload, outputDir = artifactsDir) {
  fs.mkdirSync(outputDir, { recursive: true });
  const outputPath = path.join(outputDir, `${name}.json`);
  fs.writeFileSync(outputPath, `${JSON.stringify(payload, null, 2)}\n`, "utf8");
  return outputPath;
}

export function formatSuiteListing() {
  return [...suiteOrder, "changed"]
    .map((suiteName) => {
      if (suiteName === "changed") {
        return {
          name: suiteName,
          description: "Select suites from git diff or working tree changes before validating."
        };
      }

      return {
        name: suiteName,
        description: suiteDefinitions[suiteName].description
      };
    });
}