"use strict";
// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
Object.defineProperty(exports, "__esModule", { value: true });
exports.diff = exports.DiffType = void 0;
var DiffType;
(function (DiffType) {
    DiffType["removed"] = "removed";
    DiffType["common"] = "common";
    DiffType["added"] = "added";
})(DiffType = exports.DiffType || (exports.DiffType = {}));
const REMOVED = 1;
const COMMON = 2;
const ADDED = 3;
function createCommon(A, B, reverse) {
    const common = [];
    if (A.length === 0 || B.length === 0)
        return [];
    for (let i = 0; i < Math.min(A.length, B.length); i += 1) {
        if (A[reverse ? A.length - i - 1 : i] === B[reverse ? B.length - i - 1 : i]) {
            common.push(A[reverse ? A.length - i - 1 : i]);
        }
        else {
            return common;
        }
    }
    return common;
}
/**
 * Renders the differences between the actual and expected values
 * @param A Actual value
 * @param B Expected value
 */
function diff(A, B) {
    const prefixCommon = createCommon(A, B);
    const suffixCommon = createCommon(A.slice(prefixCommon.length), B.slice(prefixCommon.length), true).reverse();
    A = suffixCommon.length
        ? A.slice(prefixCommon.length, -suffixCommon.length)
        : A.slice(prefixCommon.length);
    B = suffixCommon.length
        ? B.slice(prefixCommon.length, -suffixCommon.length)
        : B.slice(prefixCommon.length);
    const swapped = B.length > A.length;
    [A, B] = swapped ? [B, A] : [A, B];
    const M = A.length;
    const N = B.length;
    if (!M && !N && !suffixCommon.length && !prefixCommon.length)
        return [];
    if (!N) {
        return [
            ...prefixCommon.map((c) => ({ type: DiffType.common, value: c })),
            ...A.map((a) => ({
                type: swapped ? DiffType.added : DiffType.removed,
                value: a,
            })),
            ...suffixCommon.map((c) => ({ type: DiffType.common, value: c })),
        ];
    }
    const offset = N;
    const delta = M - N;
    const size = M + N + 1;
    const fp = new Array(size).fill({ y: -1 });
    /**
     * INFO:
     * This buffer is used to save memory and improve performance.
     * The first half is used to save route and last half is used to save diff
     * type.
     * This is because, when I kept new uint8array area to save type,performance
     * worsened.
     */
    const routes = new Uint32Array((M * N + size + 1) * 2);
    const diffTypesPtrOffset = routes.length / 2;
    let ptr = 0;
    let p = -1;
    function backTrace(A, B, current, swapped) {
        const M = A.length;
        const N = B.length;
        const result = [];
        let a = M - 1;
        let b = N - 1;
        let j = routes[current.id];
        let type = routes[current.id + diffTypesPtrOffset];
        while (true) {
            if (!j && !type)
                break;
            const prev = j;
            if (type === REMOVED) {
                result.unshift({
                    type: swapped ? DiffType.removed : DiffType.added,
                    value: B[b],
                });
                b -= 1;
            }
            else if (type === ADDED) {
                result.unshift({
                    type: swapped ? DiffType.added : DiffType.removed,
                    value: A[a],
                });
                a -= 1;
            }
            else {
                result.unshift({ type: DiffType.common, value: A[a] });
                a -= 1;
                b -= 1;
            }
            j = routes[prev];
            type = routes[prev + diffTypesPtrOffset];
        }
        return result;
    }
    function createFP(slide, down, k, M) {
        if (slide && slide.y === -1 && down && down.y === -1) {
            return { y: 0, id: 0 };
        }
        if ((down && down.y === -1) ||
            k === M ||
            (slide && slide.y) > (down && down.y) + 1) {
            const prev = slide.id;
            ptr++;
            routes[ptr] = prev;
            routes[ptr + diffTypesPtrOffset] = ADDED;
            return { y: slide.y, id: ptr };
        }
        else {
            const prev = down.id;
            ptr++;
            routes[ptr] = prev;
            routes[ptr + diffTypesPtrOffset] = REMOVED;
            return { y: down.y + 1, id: ptr };
        }
    }
    function snake(k, slide, down, _offset, A, B) {
        const M = A.length;
        const N = B.length;
        if (k < -N || M < k)
            return { y: -1, id: -1 };
        const fp = createFP(slide, down, k, M);
        while (fp.y + k < M && fp.y < N && A[fp.y + k] === B[fp.y]) {
            const prev = fp.id;
            ptr++;
            fp.id = ptr;
            fp.y += 1;
            routes[ptr] = prev;
            routes[ptr + diffTypesPtrOffset] = COMMON;
        }
        return fp;
    }
    while (fp[delta + offset].y < N) {
        p = p + 1;
        for (let k = -p; k < delta; ++k) {
            fp[k + offset] = snake(k, fp[k - 1 + offset], fp[k + 1 + offset], offset, A, B);
        }
        for (let k = delta + p; k > delta; --k) {
            fp[k + offset] = snake(k, fp[k - 1 + offset], fp[k + 1 + offset], offset, A, B);
        }
        fp[delta + offset] = snake(delta, fp[delta - 1 + offset], fp[delta + 1 + offset], offset, A, B);
    }
    return [
        ...prefixCommon.map((c) => ({ type: DiffType.common, value: c })),
        ...backTrace(A, B, fp[delta + offset], swapped),
        ...suffixCommon.map((c) => ({ type: DiffType.common, value: c })),
    ];
}
exports.diff = diff;
