import { describe, it } from "@suaveplan/testing/runner";
import * as fc from "fast-check";
import { createCommand } from "../../src/command/command.js";
import { compressHistory } from "../../src/compression/history-compressor.js";
import { UndoStack } from "../../src/stack/stack.js";

interface Counter {
    value: number;
}

describe("property: compressHistory idempotency", () => {
    it("re-compressing does not change state or exceed original size", {
        timeout: 30000,
    }, () => {
        fc.assert(
            fc.property(
                fc.integer({ min: 0, max: 50 }),
                fc.integer({ min: 1, max: 20 }),
                (pushCount, depth) => {
                    const s = new UndoStack<Counter>({ value: 0 });
                    for (let i = 0; i < pushCount; i++) {
                        s.push(
                            createCommand(
                                "Inc",
                                (st) => ({ value: st.value + 1 }),
                                (st) => ({ value: st.value - 1 })
                            )
                        );
                    }
                    const r1 = compressHistory(s, { compressionDepth: depth });
                    const r2 = compressHistory(r1.stack, {
                        compressionDepth: depth,
                    });
                    // State preserved
                    if (r1.stack.current.value !== r2.stack.current.value)
                        return false;
                    // Second compression adds no new squashes (all same-label entries already merged)
                    // Size should not increase
                    return r2.newSize <= r1.newSize;
                }
            ),
            { numRuns: 200 }
        );
    });
});