import { describe, expect, it } from "@suaveplan/testing/runner";
import { FSM_CODES, FSMError } from "../errors/fsm-error.js";
import { validateDefinition } from "./definition-validator.js";

describe("validateDefinition", () => {
    it("accepts a valid minimal definition", { timeout: 5000 }, () => {
        expect(() =>
            validateDefinition({
                initial: "idle",
                context: {},
                states: { idle: {} },
            })
        ).not.toThrow();
    });

    it("accepts a valid multi-state definition", { timeout: 5000 }, () => {
        expect(() =>
            validateDefinition({
                initial: "red",
                context: {},
                states: {
                    red: { on: { NEXT: { target: "green" } } },
                    green: { on: { NEXT: { target: "yellow" } } },
                    yellow: { on: { NEXT: { target: "red" } } },
                },
            })
        ).not.toThrow();
    });

    it("throws INVALID_DEFINITION when initial state does not exist", {
        timeout: 5000,
    }, () => {
        let err: FSMError | undefined;
        try {
            validateDefinition({
                initial: "ghost",
                context: {},
                states: { idle: {} },
            });
        } catch (e) {
            err = e as FSMError;
        }
        expect(err).toBeInstanceOf(FSMError);
        expect(err?.code).toBe(FSM_CODES.INVALID_DEFINITION);
        expect(err?.message).toContain("ghost");
    });

    it("throws INVALID_DEFINITION when transition targets non-existent state", {
        timeout: 5000,
    }, () => {
        let err: FSMError | undefined;
        try {
            validateDefinition({
                initial: "idle",
                context: {},
                states: {
                    idle: { on: { GO: { target: "nowhere" } } },
                },
            });
        } catch (e) {
            err = e as FSMError;
        }
        expect(err).toBeInstanceOf(FSMError);
        expect(err?.code).toBe(FSM_CODES.INVALID_DEFINITION);
        expect(err?.message).toContain("nowhere");
    });

    it("accepts multiple transition candidates for the same event", {
        timeout: 5000,
    }, () => {
        expect(() =>
            validateDefinition({
                initial: "idle",
                context: { count: 0 },
                states: {
                    idle: {
                        on: {
                            GO: [{ target: "active" }, { target: "inactive" }],
                        },
                    },
                    active: {},
                    inactive: {},
                },
            })
        ).not.toThrow();
    });

    it("throws when nested initial child does not exist", {
        timeout: 5000,
    }, () => {
        let err: FSMError | undefined;
        try {
            validateDefinition({
                initial: "form",
                context: {},
                states: {
                    form: {
                        initial: "step999",
                        states: {
                            step1: {},
                        },
                    },
                },
            });
        } catch (e) {
            err = e as FSMError;
        }
        expect(err).toBeInstanceOf(FSMError);
        expect(err?.code).toBe(FSM_CODES.INVALID_DEFINITION);
        expect(err?.message).toContain("step999");
    });

    it("throws when nested states exist but no initial is declared", {
        timeout: 5000,
    }, () => {
        let err: FSMError | undefined;
        try {
            validateDefinition({
                initial: "form",
                context: {},
                states: {
                    form: {
                        states: {
                            step1: {},
                        },
                        // initial deliberately omitted
                    },
                },
            });
        } catch (e) {
            err = e as FSMError;
        }
        expect(err).toBeInstanceOf(FSMError);
        expect(err?.code).toBe(FSM_CODES.INVALID_DEFINITION);
    });

    it("accepts a valid nested definition with correct initial", {
        timeout: 5000,
    }, () => {
        expect(() =>
            validateDefinition({
                initial: "form",
                context: {},
                states: {
                    form: {
                        initial: "step1",
                        states: {
                            step1: { on: { NEXT: { target: "step2" } } },
                            step2: {},
                        },
                    },
                },
            })
        ).not.toThrow();
    });

    it("throws when a transition target in nested states is unknown", {
        timeout: 5000,
    }, () => {
        let err: FSMError | undefined;
        try {
            validateDefinition({
                initial: "form",
                context: {},
                states: {
                    form: {
                        initial: "step1",
                        states: {
                            step1: { on: { GO: { target: "ghost" } } },
                        },
                    },
                },
            });
        } catch (e) {
            err = e as FSMError;
        }
        expect(err).toBeInstanceOf(FSMError);
        expect(err?.code).toBe(FSM_CODES.INVALID_DEFINITION);
    });
});