import { describe, it, expect } from "bun:test";
import { chessPlugin } from "./plugin";
import { gameRegistry } from "../registry";

const PLAYER_WHITE = "player1";
const PLAYER_BLACK = "player2";

describe("chessPlugin", () => {
    describe("metadata", () => {
        it("should have correct slug and player counts", () => {
            expect(chessPlugin.slug).toBe("chess");
            expect(chessPlugin.minPlayers).toBe(2);
            expect(chessPlugin.maxPlayers).toBe(2);
        });
    });

    describe("createInitialState", () => {
        it("should create initial FEN position", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            expect(state.fen).toBe("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
            expect(state.players.white).toBe(PLAYER_WHITE);
            expect(state.players.black).toBe(PLAYER_BLACK);
            expect(state.moveHistory).toEqual([]);
            expect(state.status).toBe("playing");
        });
    });

    describe("handleAction — move", () => {
        it("should allow a legal pawn move", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.handleAction(state, { type: "move", from: "e2", to: "e4" }, PLAYER_WHITE);
            expect(result.ok).toBe(true);
            if (result.ok) {
                expect(result.state.fen).not.toBe(state.fen);
                expect(result.state.moveHistory).toEqual(["e4"]);
            }
        });

        it("should reject move when it is not the player's turn", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.handleAction(state, { type: "move", from: "e7", to: "e5" }, PLAYER_BLACK);
            expect(result.ok).toBe(false);
        });

        it("should reject an illegal move", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.handleAction(state, { type: "move", from: "e2", to: "e5" }, PLAYER_WHITE);
            expect(result.ok).toBe(false);
        });

        it("should reject a non-player's move", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.handleAction(state, { type: "move", from: "e2", to: "e4" }, "random_player");
            expect(result.ok).toBe(false);
        });

        it("should detect checkmate", () => {
            // Scholar's mate: 1.e4 e5 2.Bc4 Nc6 3.Qh5 Nf6 4.Qxf7#
            let state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const moves = [
                { player: PLAYER_WHITE, from: "e2", to: "e4" },
                { player: PLAYER_BLACK, from: "e7", to: "e5" },
                { player: PLAYER_WHITE, from: "f1", to: "c4" },
                { player: PLAYER_BLACK, from: "b8", to: "c6" },
                { player: PLAYER_WHITE, from: "d1", to: "h5" },
                { player: PLAYER_BLACK, from: "g8", to: "f6" },
                { player: PLAYER_WHITE, from: "h5", to: "f7" },
            ];
            for (const m of moves) {
                const result = chessPlugin.handleAction(state, { type: "move", from: m.from, to: m.to }, m.player);
                expect(result.ok).toBe(true);
                if (result.ok) state = result.state;
            }
            expect(state.status).toBe("checkmate");
            expect(state.winner).toBe(PLAYER_WHITE);
        });
    });

    describe("handleAction — forfeit", () => {
        it("should end the game with the other player as winner", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.handleAction(state, { type: "forfeit" }, PLAYER_WHITE);
            expect(result.ok).toBe(true);
            if (result.ok) {
                expect(result.state.status).toBe("forfeit");
                expect(result.state.winner).toBe(PLAYER_BLACK);
            }
        });
    });

    describe("getPlayerView", () => {
        it("should return full state", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const view = chessPlugin.getPlayerView(state, PLAYER_WHITE);
            expect(view).toEqual(state);
        });
    });

    describe("isGameOver", () => {
        it("should return null for ongoing game", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            expect(chessPlugin.isGameOver!(state)).toBeNull();
        });

        it("should return winner for forfeit", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            state.status = "forfeit";
            state.winner = PLAYER_BLACK;
            expect(chessPlugin.isGameOver!(state)).toEqual({ winner: PLAYER_BLACK, reason: "forfeit" });
        });
    });

    describe("onPlayerDisconnect", () => {
        it("should forfeit the disconnected player", () => {
            const state = chessPlugin.createInitialState([PLAYER_WHITE, PLAYER_BLACK]);
            const result = chessPlugin.onPlayerDisconnect!(state, PLAYER_WHITE);
            expect(result.status).toBe("forfeit");
            expect(result.winner).toBe(PLAYER_BLACK);
        });
    });

    describe("chess registration", () => {
        it("should register and retrieve from gameRegistry", () => {
            gameRegistry.register(chessPlugin);
            expect(gameRegistry.get("chess")).toBe(chessPlugin);
            expect(gameRegistry.list()).toContain(chessPlugin);
        });
    });
});