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

// Feature: multi-cli-backend, Property: Pi backend required flags
// Validates Pi-specific CLI argument construction

/**
 * 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): PiBackend {
    const config: BackendAdapterConfig = {
        cliPath: "pi",
        workingDir: "/tmp",
        queryTimeoutMs: 60000,
        allowedTools: [],
        maxTurns: 25,
        model,
    };
    return new PiBackend(config);
}

describe("Pi backend required flags", () => {
    it("generated args always contain -p for print mode", () => {
        fc.assert(
            fc.property(
                nonEmptyString,
                (prompt) => {
                    const backend = createBackend();
                    const args = backend.buildArgs(prompt);

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

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

                    const modeIndex = args.indexOf("--mode");
                    return modeIndex !== -1 && args[modeIndex + 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 },
        );
    });

    it("generated args contain --no-session for headless usage", () => {
        fc.assert(
            fc.property(
                nonEmptyString,
                (prompt) => {
                    const backend = createBackend();
                    const args = backend.buildArgs(prompt);

                    return args.includes("--no-session");
                },
            ),
            { numRuns: 100 },
        );
    });

    it("generated args contain --no-extensions, --no-skills, --no-themes for deterministic runs", () => {
        fc.assert(
            fc.property(
                nonEmptyString,
                (prompt) => {
                    const backend = createBackend();
                    const args = backend.buildArgs(prompt);

                    return (
                        args.includes("--no-extensions") &&
                        args.includes("--no-skills") &&
                        args.includes("--no-themes")
                    );
                },
            ),
            { numRuns: 100 },
        );
    });

    it("prompt is always the last argument", () => {
        fc.assert(
            fc.property(
                nonEmptyString,
                (prompt) => {
                    const backend = createBackend();
                    const args = backend.buildArgs(prompt);

                    return args[args.length - 1] === prompt;
                },
            ),
            { numRuns: 100 },
        );
    });
});