import { LessonTask } from "./MoveOutcome";

export type RuleId = "board" | "sowing" | "extraTurn" | "evenCapture" | "emptyPitCapture" | "endOfGame" | "clock";

// A rule shown on a board: the position, player 1 (bottom) to move, and the pit played, if any.
export interface RuleExample {
    board: number[];
    pitIndex?: number;
}

// The rule taught on a prepared position (player 1, bottom, to move) with a task.
export interface Lesson {
    board: number[];
    task: LessonTask;
    taskKey: string;
}

export interface Rule {
    id: RuleId;
    titleKey: string;
    // At most three sentences.
    textKeys: string[];
    example?: RuleExample;
    lesson?: Lesson;
}

const START = [4, 4, 4, 4, 4, 4, 0, 4, 4, 4, 4, 4, 4, 0];
const SOWING = [4, 4, 1, 4, 4, 4, 1, 4, 4, 4, 4, 4, 4, 2];
const EVEN_CAPTURE = [4, 4, 4, 4, 4, 4, 0, 4, 3, 4, 4, 4, 4, 1];
const EMPTY_PIT_CAPTURE = [2, 0, 4, 4, 4, 4, 3, 4, 4, 4, 4, 5, 4, 2];
const END_OF_GAME = [0, 0, 0, 0, 0, 1, 20, 2, 3, 1, 0, 2, 1, 18];

const texts = (id: string, count: number) => Array.from({ length: count }, (_, i) => `Rule${id}Text${i + 1}`);

// The rules of the game in the order they are taught (docs/specs/tutorial). Every board here is checked against the
// engine by the tests; the boards after a move are never written by hand.
export const RULES: Rule[] = [
    {
        id: "board", titleKey: "RuleBoardTitle", textKeys: texts("Board", 3),
        example: { board: START },
        lesson: { board: START, task: "anyMove", taskKey: "LessonTaskAnyMove" },
    },
    {
        id: "sowing", titleKey: "RuleSowingTitle", textKeys: texts("Sowing", 3),
        example: { board: SOWING, pitIndex: 0 },
        lesson: { board: SOWING, task: "anyMove", taskKey: "LessonTaskSowing" },
    },
    {
        id: "extraTurn", titleKey: "RuleExtraTurnTitle", textKeys: texts("ExtraTurn", 2),
        example: { board: START, pitIndex: 3 },
        lesson: { board: START, task: "extraTurn", taskKey: "LessonTaskExtraTurn" },
    },
    {
        id: "evenCapture", titleKey: "RuleEvenCaptureTitle", textKeys: texts("EvenCapture", 2),
        example: { board: EVEN_CAPTURE, pitIndex: 5 },
        lesson: { board: EVEN_CAPTURE, task: "evenCapture", taskKey: "LessonTaskEvenCapture" },
    },
    {
        id: "emptyPitCapture", titleKey: "RuleEmptyPitCaptureTitle", textKeys: texts("EmptyPitCapture", 2),
        example: { board: EMPTY_PIT_CAPTURE, pitIndex: 0 },
        lesson: { board: EMPTY_PIT_CAPTURE, task: "emptyPitCapture", taskKey: "LessonTaskEmptyPitCapture" },
    },
    {
        id: "endOfGame", titleKey: "RuleEndOfGameTitle", textKeys: texts("EndOfGame", 3),
        example: { board: END_OF_GAME, pitIndex: 5 },
        lesson: { board: END_OF_GAME, task: "endGame", taskKey: "LessonTaskEndGame" },
    },
    {
        id: "clock", titleKey: "RuleClockTitle", textKeys: texts("Clock", 2),
    },
];

export const LESSON_RULES: Rule[] = RULES.filter((rule) => rule.lesson);

export function getRule(id: string | undefined): Rule | undefined {
    return RULES.find((rule) => rule.id === id);
}

// The lesson after the given one, or undefined after the last.
export function getNextLessonRule(id: RuleId): Rule | undefined {
    const index = LESSON_RULES.findIndex((rule) => rule.id === id);
    return index >= 0 ? LESSON_RULES[index + 1] : undefined;
}