import { Change } from 'diff';

import { Context } from './context';

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

import { highlightChangesInLine } from './highlightChangesInLine';

import { highlightSyntaxInLine } from './highlightSyntaxInLine';

import { iterFitTextToWidth } from './iterFitTextToWidth';

import { ThemeColor } from './themes';

// Assuming people aren't editing lines >=100k lines

const LINE_NUMBER_WIDTH = 5;

export async function* formatAndFitHunkLine(

context: Context,

lineWidth: number,

fileName: string,

lineNo: number,

line: string | null,

changes: Change[] | null

): AsyncIterable<FormattedString> {

const {

MISSING_LINE_COLOR,

DELETED_LINE_COLOR,

DELETED_LINE_NO_COLOR,

INSERTED_LINE_COLOR,

INSERTED_LINE_NO_COLOR,

UNMODIFIED_LINE_COLOR,

UNMODIFIED_LINE_NO_COLOR,

} = context;

const blankLine = ''.padStart(lineWidth);

// A line number of 0 happens when we read the "No newline at end of file"

// message as a line at the end of a deleted/inserted file.

if (line === null || lineNo === 0) {

yield T().appendString(blankLine, MISSING_LINE_COLOR);

return;

}

const linePrefix = line.slice(0, 1);

const lineText = line.slice(1);

let lineColor: ThemeColor;

let lineNoColor: ThemeColor;

switch (linePrefix) {

case '-':

lineColor = DELETED_LINE_COLOR;

lineNoColor = DELETED_LINE_NO_COLOR;

break;

case '+':

lineColor = INSERTED_LINE_COLOR;

lineNoColor = INSERTED_LINE_NO_COLOR;

break;

default:

lineColor = UNMODIFIED_LINE_COLOR;

lineNoColor = UNMODIFIED_LINE_NO_COLOR;

break;

}

/*

Each line is rendered as follows:

<lineNo> <linePrefix> <lineText>

So LINE_NUMBER_WIDTH + 2 + 1 + 1 + lineTextWidth = lineWidth

*/

const lineTextWidth = lineWidth - 2 - 1 - 1 - LINE_NUMBER_WIDTH;

let isFirstLine = true;

const formattedLine = T().appendString(lineText);

highlightChangesInLine(context, linePrefix, formattedLine, changes);

if (context.HIGHLIGHTER && context.SYNTAX_HIGHLIGHTING_THEME) {

await highlightSyntaxInLine(

formattedLine,

fileName,

context.HIGHLIGHTER,

context.SYNTAX_HIGHLIGHTING_THEME

);

}

for (const fittedLine of iterFitTextToWidth(

context,

formattedLine,

lineTextWidth

)) {

const lineNoText =

(isFirstLine ? lineNo.toString() : '').padStart(LINE_NUMBER_WIDTH) +

' ';

const wrappedLinePrefix = (isFirstLine ? linePrefix : '')

.padStart(2)

.padEnd(3);

const hunkLine = T()

.appendString(lineNoText, lineNoColor)

.appendString(wrappedLinePrefix)

.appendSpannedString(fittedLine);

hunkLine.addSpan(0, hunkLine.getString().length, lineColor);

yield hunkLine;

isFirstLine = false;

}

}