import { Change } from 'diff';

import { Context } from './context';

import { formatAndFitHunkLine } from './formatAndFitHunkLine';

import { T, FormattedString } from './formattedString';

import { zip, zipAsync } from './zip';

import { HunkPart } from './iterFormatHunk';

export async function* iterFormatHunkSplit(

context: Context,

hunkParts: HunkPart[],

lineChanges: (Change[] | null)[]

): AsyncIterable<FormattedString> {

const { MISSING_LINE_COLOR } = context;

const lineWidth = Math.floor(context.SCREEN_WIDTH / hunkParts.length);

const blankLine = ''.padStart(lineWidth);

const lineNos = hunkParts.map((part) => part.startLineNo);

const numDeletes = hunkParts.map(() => 0);

for (const [changes, ...hunkPartLines] of zip(

lineChanges,

...hunkParts.map((part) => part.lines)

)) {

// Count deletions and adjust line numbers for previous deletions

hunkPartLines.forEach((hunkPartLine, i) => {

const prefix = hunkPartLine?.slice(0, 1) ?? null;

if (prefix === '-') {

numDeletes[i]++;

} else {

lineNos[i] -= numDeletes[i];

numDeletes[i] = 0;

}

});

const formattedLineIterables = hunkPartLines.map((hunkPartLine, i) =>

formatAndFitHunkLine(

context,

lineWidth,

hunkParts[i].fileName,

lineNos[i],

hunkPartLine ?? null,

changes ?? null

)

);

const missingLine = T().appendString(blankLine, MISSING_LINE_COLOR);

for await (const formattedLines of zipAsync(

...formattedLineIterables

)) {

const formattedLine = T();

for (const line of formattedLines) {

formattedLine.appendSpannedString(line ?? missingLine);

}

yield formattedLine;

}

hunkPartLines.forEach((hunkPartLine, i) => {

if (hunkPartLine !== null && hunkPartLine !== undefined) {

lineNos[i]++;

}

});

}

}