/**
 * Tests the voyage-code-3 default contract in setup-gbrain's PGLite init
 * sequences. The contract lives in the skill TEMPLATE (.tmpl), not in a TS
 * helper — the skill follows AI-readable instructions.
 *
 * Contract (asserted here):
 *   1. When VOYAGE_API_KEY is set, gstack's PGLite init passes
 *      --embedding-model voyage:voyage-code-3 --embedding-dimensions 1024
 *   2. When VOYAGE_API_KEY is unset, those flags are omitted (gbrain's
 *      auto-selected provider chain takes over)
 *
 * Why a separate file from gbrain-init-rollback.test.ts: that file owns the
 * .bak-rollback contract (Step 1.5 / 4.5 plan D7). This file owns the
 * embedding-model selection contract. Both extract bash from the skill
 * template and execute it against a fake gbrain.
 *
 * The fake gbrain records argv to a sentinel file so the test can assert
 * exact flags. No Voyage API calls are made.
 */

import { describe, it, expect } from "bun:test";
import {
  mkdtempSync,
  mkdirSync,
  writeFileSync,
  readFileSync,
  rmSync,
  chmodSync,
} from "fs";
import { tmpdir } from "os";
import { join } from "path";
import { spawnSync } from "child_process";

interface FakeEnv {
  tmp: string;
  home: string;
  bindir: string;
  argvLog: string;
  cleanup: () => void;
}

interface ShellCase {
  name: "bash" | "zsh";
  command: string;
  available: boolean;
}

function shellAvailable(command: string): boolean {
  const result = spawnSync(command, ["-c", "exit 0"], {
    stdio: "ignore",
  });
  return result.status === 0;
}

const SHELLS: ShellCase[] = [
  { name: "bash", command: "bash", available: shellAvailable("bash") },
  { name: "zsh", command: "zsh", available: shellAvailable("zsh") },
];

function makeFakeEnv(): FakeEnv {
  const tmp = mkdtempSync(join(tmpdir(), "gbrain-voyage-init-"));
  const home = join(tmp, "home");
  const bindir = join(tmp, "bin");
  const argvLog = join(tmp, "gbrain-argv.log");
  mkdirSync(join(home, ".gbrain"), { recursive: true });
  mkdirSync(bindir, { recursive: true });

  // Fake gbrain logs every argv invocation to argvLog (one line per call),
  // succeeds on init (writes a sentinel pglite config), and returns canned
  // output for --version. Nothing else is needed for the shape test.
  const fake = `#!/bin/sh
{
  echo "__CALL__"
  for arg in "$@"; do
    printf 'arg=%s\\n' "$arg"
  done
  echo "__END__"
} >> "${argvLog}"
case "$1" in
  --version)
    echo "gbrain 0.37.1.0"
    exit 0
    ;;
  init)
    cat > "${home}/.gbrain/config.json" <<JSON
{"engine":"pglite","database_path":"${home}/.gbrain/brain.pglite"}
JSON
    echo '{"status":"success","engine":"pglite","pages":0}'
    exit 0
    ;;
esac
exit 0
`;
  writeFileSync(join(bindir, "gbrain"), fake);
  chmodSync(join(bindir, "gbrain"), 0o755);

  return {
    tmp,
    home,
    bindir,
    argvLog,
    cleanup: () => rmSync(tmp, { recursive: true, force: true }),
  };
}

/**
 * Verbatim reimplementation of the skill template's voyage-code-3 conditional.
 * The template (setup-gbrain/SKILL.md.tmpl Path 3, Step 1.5 inside the
 * rollback wrapper, Step 4.5 Path 4 Yes branch) instructs the model to execute
 * this shell; we execute the same shell here and assert the argv passed to
 * gbrain matches the contract under both bash and zsh.
 *
 * If the template changes the flag set or the env-var name, this test
 * should fail until the shell here is updated too — by design.
 */
function runInitWithVoyageGate(
  env: FakeEnv,
  voyageKey: string | undefined,
  shell: ShellCase,
): string[][] {
  const script = `
set -u
if [ -n "\${VOYAGE_API_KEY:-}" ]; then
  gbrain init --pglite --json --embedding-model voyage:voyage-code-3 --embedding-dimensions 1024
else
  gbrain init --pglite --json
fi
`;
  const baseEnv: Record<string, string> = {
    ...process.env,
    HOME: env.home,
    PATH: `${env.bindir}:/usr/bin:/bin`,
  };
  if (voyageKey === undefined) {
    delete baseEnv.VOYAGE_API_KEY;
  } else {
    baseEnv.VOYAGE_API_KEY = voyageKey;
  }
  const result = spawnSync(shell.command, ["-c", script], {
    encoding: "utf-8",
    env: baseEnv,
  });
  if (result.status !== 0) {
    throw new Error(
      `${shell.name} init script exited ${result.status}: ${result.stderr}`,
    );
  }
  return parseArgvLog(env.argvLog);
}

function parseArgvLog(argvLog: string): string[][] {
  const calls: string[][] = [];
  let current: string[] | undefined;

  for (const line of readFileSync(argvLog, "utf-8").trim().split("\n")) {
    if (line === "__CALL__") {
      current = [];
      continue;
    }
    if (line === "__END__") {
      if (current) calls.push(current);
      current = undefined;
      continue;
    }
    if (current && line.startsWith("arg=")) {
      current.push(line.slice("arg=".length));
    }
  }

  return calls;
}

describe("voyage-code-3 default for gstack-driven PGLite init", () => {
  for (const shell of SHELLS) {
    const describeShell = shell.available ? describe : describe.skip;

    describeShell(`under ${shell.name}`, () => {
      it("passes voyage-code-3 flags as four separate argv entries when VOYAGE_API_KEY is set", () => {
        const env = makeFakeEnv();
        try {
          const calls = runInitWithVoyageGate(env, "vk_test_set", shell);
          expect(calls).toEqual([
            [
              "init",
              "--pglite",
              "--json",
              "--embedding-model",
              "voyage:voyage-code-3",
              "--embedding-dimensions",
              "1024",
            ],
          ]);
        } finally {
          env.cleanup();
        }
      });

      it("omits voyage flags when VOYAGE_API_KEY is unset", () => {
        const env = makeFakeEnv();
        try {
          const calls = runInitWithVoyageGate(env, undefined, shell);
          expect(calls).toEqual([["init", "--pglite", "--json"]]);
        } finally {
          env.cleanup();
        }
      });

      it("treats empty-string VOYAGE_API_KEY the same as unset (no false positive)", () => {
        const env = makeFakeEnv();
        try {
          const calls = runInitWithVoyageGate(env, "", shell);
          expect(calls).toEqual([["init", "--pglite", "--json"]]);
        } finally {
          env.cleanup();
        }
      });
    });
  }
});

describe("template alignment: the .tmpl actually contains the voyage gate", () => {
  // Belt-and-suspenders: if someone edits the template and drops the
  // VOYAGE_API_KEY conditional without updating the test above, this catches
  // it. The shell snippet under test must literally appear in the .tmpl.
  const TEMPLATE_PATH = join(import.meta.dir, "..", "setup-gbrain", "SKILL.md.tmpl");
  const tmpl = readFileSync(TEMPLATE_PATH, "utf-8");

  it("setup-gbrain template gates the embedding-model flag on VOYAGE_API_KEY without word-splitting", () => {
    // Should appear at least once (currently 3 init sites use the same gate).
    expect(tmpl).toContain('if [ -n "${VOYAGE_API_KEY:-}" ]; then');
    expect(tmpl).toContain(
      "gbrain init --pglite --json --embedding-model voyage:voyage-code-3 --embedding-dimensions 1024",
    );
    expect(tmpl).not.toContain("GBRAIN_EMBED_FLAGS");
  });

  it("setup-gbrain template uses the conditional gate at all 3 PGLite init sites", () => {
    // Count the gate occurrences. If a future edit adds/removes a PGLite
    // init site, update this expectation deliberately.
    const matches = tmpl.match(/if \[ -n "\$\{VOYAGE_API_KEY:-\}" \]; then/g);
    expect(matches?.length).toBe(3);

    const voyageInitMatches = tmpl.match(
      /gbrain init --pglite --json --embedding-model voyage:voyage-code-3 --embedding-dimensions 1024/g,
    );
    expect(voyageInitMatches?.length).toBe(3);
  });
});