/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
import { OffsetRange } from '../../core/offsetRange.js';
import { SequenceDiff } from './diffAlgorithm.js';
export function optimizeSequenceDiffs(sequence1, sequence2, sequenceDiffs) {
    let result = sequenceDiffs;
    result = joinSequenceDiffs(sequence1, sequence2, result);
    result = shiftSequenceDiffs(sequence1, sequence2, result);
    return result;
}
export function smoothenSequenceDiffs(sequence1, sequence2, sequenceDiffs) {
    const result = [];
    for (const s of sequenceDiffs) {
        const last = result[result.length - 1];
        if (!last) {
            result.push(s);
            continue;
        }
        if (s.seq1Range.start - last.seq1Range.endExclusive <= 2 || s.seq2Range.start - last.seq2Range.endExclusive <= 2) {
            result[result.length - 1] = new SequenceDiff(last.seq1Range.join(s.seq1Range), last.seq2Range.join(s.seq2Range));
        }
        else {
            result.push(s);
        }
    }
    return result;
}
/**
 * This function fixes issues like this:
 * ```
 * import { Baz, Bar } from "foo";
 * ```
 * <->
 * ```
 * import { Baz, Bar, Foo } from "foo";
 * ```
 * Computed diff: [ {Add "," after Bar}, {Add "Foo " after space} }
 * Improved diff: [{Add ", Foo" after Bar}]
 */
export function joinSequenceDiffs(sequence1, sequence2, sequenceDiffs) {
    if (sequenceDiffs.length === 0) {
        return sequenceDiffs;
    }
    const result = [];
    result.push(sequenceDiffs[0]);
    // First move them all to the left as much as possible and join them if possible
    for (let i = 1; i < sequenceDiffs.length; i++) {
        const prevResult = result[result.length - 1];
        let cur = sequenceDiffs[i];
        if (cur.seq1Range.isEmpty || cur.seq2Range.isEmpty) {
            const length = cur.seq1Range.start - prevResult.seq1Range.endExclusive;
            let d;
            for (d = 1; d <= length; d++) {
                if (sequence1.getElement(cur.seq1Range.start - d) !== sequence1.getElement(cur.seq1Range.endExclusive - d) ||
                    sequence2.getElement(cur.seq2Range.start - d) !== sequence2.getElement(cur.seq2Range.endExclusive - d)) {
                    break;
                }
            }
            d--;
            if (d === length) {
                // Merge previous and current diff
                result[result.length - 1] = new SequenceDiff(new OffsetRange(prevResult.seq1Range.start, cur.seq1Range.endExclusive - length), new OffsetRange(prevResult.seq2Range.start, cur.seq2Range.endExclusive - length));
                continue;
            }
            cur = cur.delta(-d);
        }
        result.push(cur);
    }
    const result2 = [];
    // Then move them all to the right and join them again if possible
    for (let i = 0; i < result.length - 1; i++) {
        const nextResult = result[i + 1];
        let cur = result[i];
        if (cur.seq1Range.isEmpty || cur.seq2Range.isEmpty) {
            const length = nextResult.seq1Range.start - cur.seq1Range.endExclusive;
            let d;
            for (d = 0; d < length; d++) {
                if (sequence1.getElement(cur.seq1Range.start + d) !== sequence1.getElement(cur.seq1Range.endExclusive + d) ||
                    sequence2.getElement(cur.seq2Range.start + d) !== sequence2.getElement(cur.seq2Range.endExclusive + d)) {
                    break;
                }
            }
            if (d === length) {
                // Merge previous and current diff, write to result!
                result[i + 1] = new SequenceDiff(new OffsetRange(cur.seq1Range.start + length, nextResult.seq1Range.endExclusive), new OffsetRange(cur.seq2Range.start + length, nextResult.seq2Range.endExclusive));
                continue;
            }
            if (d > 0) {
                cur = cur.delta(d);
            }
        }
        result2.push(cur);
    }
    if (result.length > 0) {
        result2.push(result[result.length - 1]);
    }
    return result2;
}
// align character level diffs at whitespace characters
// import { IBar } from "foo";
// import { I[Arr, I]Bar } from "foo";
// ->
// import { [IArr, ]IBar } from "foo";
// import { ITransaction, observableValue, transaction } from 'vs/base/common/observable';
// import { ITransaction, observable[FromEvent, observable]Value, transaction } from 'vs/base/common/observable';
// ->
// import { ITransaction, [observableFromEvent, ]observableValue, transaction } from 'vs/base/common/observable';
// collectBrackets(level + 1, levelPerBracketType);
// collectBrackets(level + 1, levelPerBracket[ + 1, levelPerBracket]Type);
// ->
// collectBrackets(level + 1, [levelPerBracket + 1, ]levelPerBracketType);
export function shiftSequenceDiffs(sequence1, sequence2, sequenceDiffs) {
    if (!sequence1.getBoundaryScore || !sequence2.getBoundaryScore) {
        return sequenceDiffs;
    }
    for (let i = 0; i < sequenceDiffs.length; i++) {
        const prevDiff = (i > 0 ? sequenceDiffs[i - 1] : undefined);
        const diff = sequenceDiffs[i];
        const nextDiff = (i + 1 < sequenceDiffs.length ? sequenceDiffs[i + 1] : undefined);
        const seq1ValidRange = new OffsetRange(prevDiff ? prevDiff.seq1Range.start + 1 : 0, nextDiff ? nextDiff.seq1Range.endExclusive - 1 : sequence1.length);
        const seq2ValidRange = new OffsetRange(prevDiff ? prevDiff.seq2Range.start + 1 : 0, nextDiff ? nextDiff.seq2Range.endExclusive - 1 : sequence2.length);
        if (diff.seq1Range.isEmpty) {
            sequenceDiffs[i] = shiftDiffToBetterPosition(diff, sequence1, sequence2, seq1ValidRange, seq2ValidRange);
        }
        else if (diff.seq2Range.isEmpty) {
            sequenceDiffs[i] = shiftDiffToBetterPosition(diff.reverse(), sequence2, sequence1, seq2ValidRange, seq1ValidRange).reverse();
        }
    }
    return sequenceDiffs;
}
function shiftDiffToBetterPosition(diff, sequence1, sequence2, seq1ValidRange, seq2ValidRange) {
    const maxShiftLimit = 100; // To prevent performance issues
    // don't touch previous or next!
    let deltaBefore = 1;
    while (diff.seq1Range.start - deltaBefore >= seq1ValidRange.start &&
        diff.seq2Range.start - deltaBefore >= seq2ValidRange.start &&
        sequence2.getElement(diff.seq2Range.start - deltaBefore) ===
            sequence2.getElement(diff.seq2Range.endExclusive - deltaBefore) && deltaBefore < maxShiftLimit) {
        deltaBefore++;
    }
    deltaBefore--;
    let deltaAfter = 0;
    while (diff.seq1Range.start + deltaAfter < seq1ValidRange.endExclusive &&
        diff.seq2Range.endExclusive + deltaAfter < seq2ValidRange.endExclusive &&
        sequence2.getElement(diff.seq2Range.start + deltaAfter) ===
            sequence2.getElement(diff.seq2Range.endExclusive + deltaAfter) && deltaAfter < maxShiftLimit) {
        deltaAfter++;
    }
    if (deltaBefore === 0 && deltaAfter === 0) {
        return diff;
    }
    // Visualize `[sequence1.text, diff.seq1Range.start + deltaAfter]`
    // and `[sequence2.text, diff.seq2Range.start + deltaAfter, diff.seq2Range.endExclusive + deltaAfter]`
    let bestDelta = 0;
    let bestScore = -1;
    // find best scored delta
    for (let delta = -deltaBefore; delta <= deltaAfter; delta++) {
        const seq2OffsetStart = diff.seq2Range.start + delta;
        const seq2OffsetEndExclusive = diff.seq2Range.endExclusive + delta;
        const seq1Offset = diff.seq1Range.start + delta;
        const score = sequence1.getBoundaryScore(seq1Offset) + sequence2.getBoundaryScore(seq2OffsetStart) + sequence2.getBoundaryScore(seq2OffsetEndExclusive);
        if (score > bestScore) {
            bestScore = score;
            bestDelta = delta;
        }
    }
    return diff.delta(bestDelta);
}
