/**
 * executor.test.ts
 * ----------------
 * Unit tests for the execution driver against a fake `Device`. Covers the
 * two sweep outcomes, on-screen reflection, the rounding/interrupt contract,
 * step pacing, and the loop/restore options — none of which was testable
 * before the device seam existed.
 */

import { describe, expect, test } from "bun:test";

import { DEFAULT_CONFIG } from "../src/config.ts";
import type { Config } from "../src/config.ts";
import type { Device, Point } from "../src/device.ts";
import { executePath, type Logger } from "../src/executor.ts";
import type { MoveContext, MovementStrategy } from "../src/strategies.ts";

const noopLog: Logger = { info: (): void => {}, event: (): void => {} };

/**
 * A scriptable `Device`. `getPosition` echoes the last commanded point
 * (simulating "the cursor stayed where we put it") unless `overrides` maps
 * the current getPosition call index to a substitute — used to inject a
 * mid-sweep user interruption.
 */
class FakeDevice implements Device {
    commanded: Point[] = [];
    sleeps: number[] = [];
    getCalls = 0;
    overrides = new Map<number, Point>();
    constructor(public w = 1920, public h = 1080, public initial: Point = { x: 0, y: 0 }) {}

    async getPosition(): Promise<Point> {
        this.getCalls++;
        const o = this.overrides.get(this.getCalls);
        if (o) return o;
        return this.commanded.at(-1) ?? this.initial;
    }
    async setPosition(p: Point): Promise<void> {
        this.commanded.push(p);
    }
    async width(): Promise<number> {
        return this.w;
    }
    async height(): Promise<number> {
        return this.h;
    }
    async sleep(ms: number): Promise<void> {
        this.sleeps.push(ms);
    }
}

/** A strategy that emits a fixed list of points. */
function fixed(points: Point[]): MovementStrategy {
    return {
        name: "fixed",
        *path(): Generator<Point> {
            yield* points;
        },
    };
}

function ctxOf(start: Point, width: number, height: number): MoveContext {
    return { start, width, height, rng: Math.random };
}

/** A full `Config` for the executor's pacing; only `stepDelay` matters here. */
function cfgOf(config?: Partial<Config>): Config {
    return { ...DEFAULT_CONFIG, ...config };
}

describe("executePath — outcomes", () => {
    test("clean sweep commands every point, restores to start, returns 'completed'", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [
            { x: 501, y: 500 },
            { x: 502, y: 500 },
            { x: 503, y: 500 },
        ];
        const outcome = await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(outcome).toBe("completed");
        // 3 steps + 1 restore.
        expect(dev.commanded).toEqual([...pts, start]);
    });

    test("interruption mid-sweep returns 'interrupted' and does NOT restore", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [
            { x: 501, y: 500 },
            { x: 502, y: 500 },
            { x: 503, y: 500 },
        ];
        // 2nd getPosition call reports the user elsewhere.
        dev.overrides.set(2, { x: 9, y: 9 });
        const outcome = await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(outcome).toBe("interrupted");
        // Commanded points 1 and 2 only; never restored to start.
        expect(dev.commanded).toEqual([pts[0]!, pts[1]!]);
        expect(dev.commanded.at(-1)).not.toEqual(start);
    });
});

describe("executePath — on-screen reflection", () => {
    test("mirrors an out-of-range coordinate back inside the inset range", async () => {
        const dev = new FakeDevice(100, 100);
        // Inset range [2, 97], span = 95; x=120 -> (120-2)=118, 190-118=72, +2 = 74.
        const pts = [{ x: 120, y: 50 }];
        await executePath(fixed(pts), ctxOf({ x: 50, y: 50 }, 100, 100), dev, noopLog, cfgOf());
        expect(dev.commanded[0]).toEqual({ x: 74, y: 50 });
    });

    test("negative and far-past-edge coordinates both fold inside", async () => {
        const dev = new FakeDevice(100, 100);
        // Inset [2, 97]. x=-5 -> reflects to 9; x=99 -> 95 (period 190).
        const pts = [
            { x: -5, y: 50 },
            { x: 99, y: 50 },
        ];
        await executePath(fixed(pts), ctxOf({ x: 50, y: 50 }, 100, 100), dev, noopLog, cfgOf());
        for (const p of dev.commanded.slice(0, 2)) {
            expect(p.x).toBeGreaterThanOrEqual(2);
            expect(p.x).toBeLessThanOrEqual(97);
        }
    });

    test("a monotonic ramp past an edge keeps moving — never two identical points in a row", async () => {
        // This is the guarantee that motivated removing `clamp`: a clamp would
        // pin every over-the-edge point to the same edge pixel, stalling the
        // cursor. Reflection folds the ramp into a triangle wave, so the cursor
        // both rises and falls and never repeats a pixel step to step.
        const dev = new FakeDevice(40, 40);
        // Ramp x well past the right edge and back's worth of travel.
        const pts = Array.from({ length: 60 }, (_, i) => ({ x: 10 + i, y: 20 }));
        await executePath(fixed(pts), ctxOf({ x: 10, y: 20 }, 40, 40), dev, noopLog, cfgOf({ stepDelay: 0 }));
        const xs = dev.commanded.slice(0, 60).map((p) => p.x);
        // No stall: consecutive commanded points always differ.
        for (let i = 1; i < xs.length; i++) {
            expect(xs[i]).not.toBe(xs[i - 1]);
        }
        // It bounced: the ramp both increased and decreased at some point.
        const rose = xs.some((x, i) => i > 0 && x > xs[i - 1]!);
        const fell = xs.some((x, i) => i > 0 && x < xs[i - 1]!);
        expect(rose && fell).toBe(true);
    });
});

describe("executePath — options", () => {
    test("restore:false leaves the cursor at the last step, no snap-back", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [
            { x: 501, y: 500 },
            { x: 502, y: 500 },
        ];
        const outcome = await executePath(
            fixed(pts),
            ctxOf(start, dev.w, dev.h),
            dev,
            noopLog,
            cfgOf(),
            { restore: false },
        );
        expect(outcome).toBe("completed");
        // No trailing restore-to-start command.
        expect(dev.commanded).toEqual(pts);
    });

    test("the default (no options) still restores to start", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [{ x: 501, y: 500 }];
        await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(dev.commanded).toEqual([...pts, start]);
    });

    test("loop:true runs loopPath when present, path otherwise", async () => {
        const dev = new FakeDevice();
        // A strategy whose loopPath differs from its path, both finite here.
        const strat: MovementStrategy = {
            name: "dual",
            *path(): Generator<Point> {
                yield { x: 1, y: 1 };
            },
            *loopPath(): Generator<Point> {
                yield { x: 10, y: 10 };
                yield { x: 20, y: 20 };
            },
        };
        await executePath(strat, ctxOf({ x: 0, y: 0 }, dev.w, dev.h), dev, noopLog, cfgOf(), {
            loop: true,
            restore: false,
        });
        expect(dev.commanded).toEqual([{ x: 10, y: 10 }, { x: 20, y: 20 }]);
    });

    test("loop:true falls back to path when the strategy has no loopPath", async () => {
        const dev = new FakeDevice();
        const strat = fixed([{ x: 3, y: 3 }]);
        await executePath(strat, ctxOf({ x: 0, y: 0 }, dev.w, dev.h), dev, noopLog, cfgOf(), {
            loop: true,
            restore: false,
        });
        expect(dev.commanded).toEqual([{ x: 3, y: 3 }]);
    });
});

describe("executePath — readback tolerance", () => {
    test("a readback within tolerance is not treated as interruption", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [
            { x: 510, y: 500 },
            { x: 520, y: 500 },
        ];
        // Each in-sweep readback lands 2px off the commanded point (OS jitter,
        // not the user). 2px is within READBACK_TOLERANCE, so the sweep runs on.
        dev.overrides.set(1, { x: 512, y: 501 });
        dev.overrides.set(2, { x: 518, y: 499 });
        const outcome = await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(outcome).toBe("completed");
        expect(dev.commanded).toEqual([...pts, start]);
    });

    test("a readback beyond tolerance is treated as interruption", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [
            { x: 510, y: 500 },
            { x: 520, y: 500 },
        ];
        // First readback is 3px off -> exceeds the 2px tolerance -> real user.
        dev.overrides.set(1, { x: 513, y: 500 });
        const outcome = await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(outcome).toBe("interrupted");
        expect(dev.commanded).toEqual([pts[0]!]);
    });
});

describe("executePath — rounding & pacing", () => {
    test("fractional targets are rounded and do not read as interruption", async () => {
        const dev = new FakeDevice();
        const start = { x: 500, y: 500 };
        const pts = [{ x: 10.4, y: 20.6 }]; // -> (10, 21)
        const outcome = await executePath(fixed(pts), ctxOf(start, dev.w, dev.h), dev, noopLog, cfgOf());
        expect(outcome).toBe("completed");
        expect(dev.commanded[0]).toEqual({ x: 10, y: 21 });
    });

    test("sleeps once per step with the configured stepDelay", async () => {
        const dev = new FakeDevice();
        const pts = [
            { x: 501, y: 500 },
            { x: 502, y: 500 },
        ];
        await executePath(fixed(pts), ctxOf({ x: 500, y: 500 }, dev.w, dev.h), dev, noopLog, cfgOf({ stepDelay: 7 }));
        expect(dev.sleeps).toEqual([7, 7]);
    });
});