import test from "node:test";
import assert from "node:assert/strict";
import fs from "node:fs";
import os from "node:os";
import path from "node:path";

const previousDataDir = process.env.DATA_DIR;
const previousDisableSqliteAutoBackup = process.env.DISABLE_SQLITE_AUTO_BACKUP;
const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-emergency-fallback-service-"));
process.env.DATA_DIR = tmpDir;
process.env.DISABLE_SQLITE_AUTO_BACKUP = "true";

const core = await import("../../src/lib/db/core.ts");

const {
  EMERGENCY_FALLBACK_CONFIG,
  shouldUseFallback,
  isFallbackDecision,
  resetEmergencyFallbackEnvCache,
} = await import("../../open-sse/services/emergencyFallback.ts");

function restoreEnv(name: string, value: string | undefined) {
  if (value === undefined) {
    delete process.env[name];
  } else {
    process.env[name] = value;
  }
}

function resetTestState() {
  core.resetDbInstance();
  fs.rmSync(tmpDir, { recursive: true, force: true });
  fs.mkdirSync(tmpDir, { recursive: true });
  delete process.env.OMNIROUTE_EMERGENCY_FALLBACK;
  resetEmergencyFallbackEnvCache();
}

test.beforeEach(() => {
  resetTestState();
});

test.afterEach(() => {
  delete process.env.OMNIROUTE_EMERGENCY_FALLBACK;
  resetEmergencyFallbackEnvCache();
});

test.after(() => {
  core.resetDbInstance();
  fs.rmSync(tmpDir, { recursive: true, force: true });
  restoreEnv("DATA_DIR", previousDataDir);
  restoreEnv("DISABLE_SQLITE_AUTO_BACKUP", previousDisableSqliteAutoBackup);
});

test("shouldUseFallback returns disabled when the feature flag is off", () => {
  const result = shouldUseFallback(402, "payment required", false, {
    ...EMERGENCY_FALLBACK_CONFIG,
    enabled: false,
  });

  assert.deepEqual(result, {
    shouldFallback: false,
    reason: "emergency fallback disabled",
  });
  assert.equal(isFallbackDecision(result), false);
});

test("shouldUseFallback skips tool requests when configured", () => {
  const result = shouldUseFallback(402, "payment required", true);

  assert.deepEqual(result, {
    shouldFallback: false,
    reason: "skipped: request has tools",
  });
});

test("shouldUseFallback triggers on HTTP 402", () => {
  const result = shouldUseFallback(402, "", false);

  assert.equal(result.shouldFallback, true);
  assert.equal(result.provider, EMERGENCY_FALLBACK_CONFIG.provider);
  assert.equal(result.model, EMERGENCY_FALLBACK_CONFIG.model);
  assert.equal(result.maxOutputTokens, EMERGENCY_FALLBACK_CONFIG.maxOutputTokens);
  assert.equal(isFallbackDecision(result), true);
});

test("shouldUseFallback matches budget keywords case-insensitively", () => {
  const result = shouldUseFallback(500, "Billing hard stop: OUT OF CREDITS", false);

  assert.equal(result.shouldFallback, true);
  assert.match(result.reason, /budget error detected/i);
  assert.match(result.reason, /(billing|out of credits)/i);
});

test("shouldUseFallback ignores keywords when keyword matching is disabled", () => {
  const result = shouldUseFallback(500, "quota_exceeded", false, {
    ...EMERGENCY_FALLBACK_CONFIG,
    triggerOnBudgetKeywords: false,
  });

  assert.deepEqual(result, {
    shouldFallback: false,
    reason: "no budget error detected",
  });
});

test("shouldUseFallback ignores HTTP 402 when status-trigger fallback is disabled", () => {
  const result = shouldUseFallback(402, "", false, {
    ...EMERGENCY_FALLBACK_CONFIG,
    triggerOn402: false,
  });

  assert.deepEqual(result, {
    shouldFallback: false,
    reason: "no budget error detected",
  });
});

test("shouldUseFallback returns no fallback for unrelated errors", () => {
  const result = shouldUseFallback(500, "temporary upstream timeout", false);

  assert.deepEqual(result, {
    shouldFallback: false,
    reason: "no budget error detected",
  });
  assert.equal(isFallbackDecision(result), false);
});