import { spawnSync } from "node:child_process";
import { lstat } from "node:fs/promises";
import path from "node:path";

import {
  ciCheckoutIdentityFailures,
  ciBuildEnvironmentFailures,
  isValidCommitSha,
  isValidSourceDateEpoch,
} from "./lib/build-environment.ts";
import { classifyGateStepResult } from "./lib/ci-step-result.ts";
import { withCiGatePreflight } from "./contracts/ci-gates.ts";
import { validateCiArtifact } from "./lib/ci-artifact-validator.ts";
import { writeCiGateLogAtomic } from "./lib/ci-gate-log.ts";

const requestedGateId = process.argv
  .slice(2)
  .find((argument) => /^FE-GATE-\d{3}$/.test(argument));
await withCiGatePreflight(
  process.cwd(),
  requestedGateId,
  async ({ contractIndex, gateId, gate }) => {

const logArtifact = contractIndex.artifacts.get(gate.logArtifactId);
if (!logArtifact) throw new TypeError(`CI gate log artifact disappeared: ${gate.logArtifactId}`);
const logSchema = contractIndex.artifactSchemas.get(logArtifact.schemaId);
if (!logSchema || logSchema.kind !== "text") {
  throw new TypeError(`CI gate log schema must be bounded text: ${logArtifact.schemaId}`);
}
const output: string[] = [];
let outputBytes = 0;
let passed = true;
const DEFAULT_STEP_TIMEOUT_MS = 30 * 60 * 1_000;
const MAX_STEP_OUTPUT_BYTES = 16 * 1024 * 1_024;
const LOG_DIAGNOSTIC_RESERVE_BYTES = 4_096;
const freshlyProducedArtifactIds = new Set<string>();
const commandGeneratedEvidence = gate.evidenceArtifactIds
  .map((artifactId) => contractIndex.artifacts.get(artifactId))
  .filter((artifact) => artifact?.production === "command-generated");

async function observeArtifactGeneration(relativePath: string): Promise<string> {
  try {
    const metadata = await lstat(path.join(process.cwd(), relativePath), {
      bigint: true,
    });
    return [
      metadata.dev,
      metadata.ino,
      metadata.size,
      metadata.mtimeNs,
      metadata.ctimeNs,
    ].join(":");
  } catch (error) {
    if ((error as NodeJS.ErrnoException).code === "ENOENT") return "missing";
    throw error;
  }
}
const appendOutput = (...values: readonly string[]): boolean => {
  for (const value of values.filter(Boolean)) {
    const addedBytes = Buffer.byteLength(value, "utf8") + 1;
    if (outputBytes + addedBytes > logSchema.maxBytes) return false;
    output.push(value);
    outputBytes += addedBytes;
  }
  return true;
};

const gateEnvironment = { ...process.env };
if (gateEnvironment.CI === "true") {
  const commitMetadata = spawnSync(
    "git",
    ["show", "-s", "--format=%H%n%ct", "HEAD"],
    { encoding: "utf8" },
  );
  const [commitSha = "", sourceDateEpoch = ""] =
    commitMetadata.stdout.trim().split(/\r?\n/);
  if (
    commitMetadata.status === 0 &&
    isValidCommitSha(commitSha) &&
    isValidSourceDateEpoch(sourceDateEpoch)
  ) {
    if (!gateEnvironment.SOURCE_DATE_EPOCH?.trim()) {
      gateEnvironment.SOURCE_DATE_EPOCH = sourceDateEpoch;
      appendOutput(`derived SOURCE_DATE_EPOCH=${sourceDateEpoch} from HEAD`);
    }
    for (const failure of ciCheckoutIdentityFailures(gateEnvironment, {
      commitSha,
      sourceDateEpoch,
    })) {
      appendOutput(failure);
      passed = false;
    }
  } else {
    appendOutput(
      "unable to resolve the checked-out commit identity and timestamp",
      commitMetadata.stderr,
    );
    passed = false;
  }
}

for (const failure of ciBuildEnvironmentFailures(gateEnvironment)) {
  appendOutput(failure);
  passed = false;
}

for (const variable of gate.requiresEnvironment ?? []) {
  if (!gateEnvironment[variable]) {
    appendOutput(`missing required environment: ${variable}`);
    passed = false;
  }
}

if (passed) {
  for (const commandId of gate.commandIds) {
    const step = contractIndex.commands.get(commandId);
    if (!step) throw new TypeError(`CI gate command disappeared after validation: ${commandId}`);
    const producedArtifacts = commandGeneratedEvidence.filter((artifact) =>
      artifact.producerCommandIds.includes(commandId)
    );
    const generationBefore = new Map(
      await Promise.all(
        producedArtifacts.map(async (artifact) => [
          artifact.id,
          await observeArtifactGeneration(artifact.path),
        ] as const),
      ),
    );
    const commandLine = `$ corepack pnpm ${step.script} ${(step.args ?? []).join(" ")}`.trim();
    if (!appendOutput(commandLine) || logSchema.maxBytes - outputBytes <= LOG_DIAGNOSTIC_RESERVE_BYTES) {
      appendOutput("gate aggregate output budget exhausted before command execution");
      passed = false;
      break;
    }
    const result = spawnSync(
      "corepack",
      ["pnpm", step.script, ...(step.args ?? [])],
      {
        encoding: "utf8",
        env: gateEnvironment,
        timeout: step.timeoutMs ?? DEFAULT_STEP_TIMEOUT_MS,
        maxBuffer: Math.min(
          MAX_STEP_OUTPUT_BYTES,
          logSchema.maxBytes - outputBytes - LOG_DIAGNOSTIC_RESERVE_BYTES,
        ),
      },
    );
    const stdout = result.stdout ?? "";
    const stderr = result.stderr ?? "";
    if (!appendOutput(stdout, stderr)) {
      appendOutput("gate aggregate output exceeded the bounded log schema");
      passed = false;
      break;
    }
    const expectation = step.expect === "pass"
      ? ({ kind: "pass" } as const)
      : step.expectedExitCode !== undefined && step.expectedDiagnosticId !== undefined
        ? ({
            kind: "fail",
            expectedExitCode: step.expectedExitCode,
            expectedDiagnosticId: step.expectedDiagnosticId,
          } as const)
        : (() => {
            throw new TypeError(`negative command lost its validated identity: ${step.id}`);
          })();
    const classification = classifyGateStepResult(expectation, {
      status: result.status,
      signal: result.signal,
      stdout,
      stderr,
      ...(result.error
        ? { error: { code: (result.error as NodeJS.ErrnoException).code } }
        : {}),
    });
    if (!appendOutput(`classification: ${classification.kind}`)) passed = false;
    if (!classification.expectationMet) {
      appendOutput(
        `expectation failed: expected ${step.expect}, exit=${result.status}, signal=${result.signal ?? "none"}`,
        ...(step.expect === "fail"
          ? [
              `expected negative fixture identity: exit=${step.expectedExitCode}, diagnostic=${JSON.stringify(step.expectedDiagnosticId)}`,
            ]
          : []),
        ...(classification.kind === "INFRASTRUCTURE_FAILURE"
          ? [`infrastructure failure: ${classification.detail}`]
          : []),
      );
      passed = false;
      break;
    }
    for (const artifact of producedArtifacts) {
      const generationAfter = await observeArtifactGeneration(artifact.path);
      if (generationAfter !== generationBefore.get(artifact.id)) {
        freshlyProducedArtifactIds.add(artifact.id);
      }
    }
  }
}

if (passed) {
  for (const artifact of commandGeneratedEvidence) {
    if (!freshlyProducedArtifactIds.has(artifact.id)) {
      appendOutput(`command-generated evidence was not freshly produced: ${artifact.path}`);
      passed = false;
    }
  }
}

await writeCiGateLogAtomic({
  root: process.cwd(),
  relativePath: logArtifact.path,
  content: `${output.filter(Boolean).join("\n")}\n`,
  maxBytes: logSchema.maxBytes,
});

if (passed) {
  const validationIds = [...new Set([gate.logArtifactId, ...gate.evidenceArtifactIds])];
  for (const artifactId of validationIds) {
    const artifact = contractIndex.artifacts.get(artifactId);
    if (!artifact) throw new TypeError(`CI artifact disappeared: ${artifactId}`);
    const schema = contractIndex.artifactSchemas.get(artifact.schemaId);
    if (!schema) throw new TypeError(`CI artifact schema disappeared: ${artifact.schemaId}`);
    try {
      await validateCiArtifact({ root: process.cwd(), artifact, schema });
      if (!appendOutput(`validated evidence: ${artifact.path} (${schema.id})`)) passed = false;
    } catch (error) {
      appendOutput(
        `invalid evidence: ${artifact.path}: ${error instanceof Error ? error.message : String(error)}`,
      );
      passed = false;
    }
  }
  if (!passed) {
    await writeCiGateLogAtomic({
      root: process.cwd(),
      relativePath: logArtifact.path,
      content: `${output.filter(Boolean).join("\n")}\n`,
      maxBytes: logSchema.maxBytes,
    });
  }
}

if (!passed) {
  process.stderr.write(`${gateId} ${gate.name}: FAIL\n`);
  process.exit(1);
}
process.stdout.write(
  `${gateId} ${gate.name}: PASS (${gate.retentionClassId})\n`,
);
  },
);