import { describe, it } from "vitest";
import fc from "fast-check";
import { OpenCodeBackend } from "../../src/backends/opencode-backend.js";
import type { BackendAdapterConfig } from "../../src/backends/types.js";

// Feature: multi-cli-backend, Property 4: OpenCode backend required flags
// **Validates: Requirements 5.2, 5.3, 5.5**

/**
 * Arbitrary for non-empty strings that won't break CLI arg parsing.
 */
const nonEmptyString = fc.string({ minLength: 1, maxLength: 200 });

/**
 * Arbitrary for model strings (provider/model format).
 */
const modelString = fc.stringMatching(/^[a-z]{1,20}\/[a-z0-9-]{1,40}$/);

function createBackend(model?: string): OpenCodeBackend {
  const config: BackendAdapterConfig = {
    cliPath: "opencode",
    workingDir: "/tmp",
    queryTimeoutMs: 60000,
    allowedTools: [],
    maxTurns: 25,
    model,
  };
  return new OpenCodeBackend(config);
}

describe("Property 4: OpenCode backend required flags", () => {
  it("generated args always start with the run subcommand", () => {
    fc.assert(
      fc.property(
        nonEmptyString,
        (prompt) => {
          const backend = createBackend();
          const args = backend.buildArgs(prompt);

          return args[0] === "run";
        },
      ),
      { numRuns: 100 },
    );
  });

  it("generated args always contain --format json", () => {
    fc.assert(
      fc.property(
        nonEmptyString,
        (prompt) => {
          const backend = createBackend();
          const args = backend.buildArgs(prompt);

          const formatIndex = args.indexOf("--format");
          return formatIndex !== -1 && args[formatIndex + 1] === "json";
        },
      ),
      { numRuns: 100 },
    );
  });

  it("generated args contain --model when a model is configured", () => {
    fc.assert(
      fc.property(
        nonEmptyString,
        modelString,
        (prompt, model) => {
          const backend = createBackend(model);
          const args = backend.buildArgs(prompt);

          const modelIndex = args.indexOf("--model");
          return modelIndex !== -1 && args[modelIndex + 1] === model;
        },
      ),
      { numRuns: 100 },
    );
  });

  it("generated args do not contain --model when no model is configured", () => {
    fc.assert(
      fc.property(
        nonEmptyString,
        (prompt) => {
          const backend = createBackend(undefined);
          const args = backend.buildArgs(prompt);

          return !args.includes("--model");
        },
      ),
      { numRuns: 100 },
    );
  });
});