function getTextEditsInternal()

in src/client/common/editor.ts [162:239]
63 lines of code
17 McCabe index (conditional complexity)

function getTextEditsInternal(before: string, diffs: [number, string][], startLine: number = 0): Edit[] {
    let line = startLine;
    let character = 0;
    const beforeLines = before.split(/\r?\n/g);
    if (line > 0) {
        beforeLines.filter((_l, i) => i < line).forEach((l) => (character += l.length + NEW_LINE_LENGTH));
    }
    const edits: Edit[] = [];
    let edit: Edit | null = null;
    let end: Position;

    for (let i = 0; i < diffs.length; i += 1) {
        let start = new Position(line, character);
        // Compute the line/character after the diff is applied.

        for (let curr = 0; curr < diffs[i][1].length; curr += 1) {
            if (diffs[i][1][curr] !== '\n') {
                character += 1;
            } else {
                character = 0;
                line += 1;
            }
        }

        const dmp = require('diff-match-patch') as typeof import('diff-match-patch');

        switch (diffs[i][0]) {
            case dmp.DIFF_DELETE:
                if (
                    beforeLines[line - 1].length === 0 &&
                    beforeLines[start.line - 1] &&
                    beforeLines[start.line - 1].length === 0
                ) {
                    // We're asked to delete an empty line which only contains `/\r?\n/g`. The last line is also empty.
                    // Delete the `\n` from the last line instead of deleting `\n` from the current line
                    // This change ensures that the last line in the file, which won't contain `\n` is deleted
                    start = new Position(start.line - 1, 0);
                    end = new Position(line - 1, 0);
                } else {
                    end = new Position(line, character);
                }
                if (edit === null) {
                    edit = new Edit(EditAction.Delete, start);
                } else if (edit.action !== EditAction.Delete) {
                    throw new Error('cannot format due to an internal error.');
                }
                edit.end = end;
                break;

            case dmp.DIFF_INSERT:
                if (edit === null) {
                    edit = new Edit(EditAction.Insert, start);
                } else if (edit.action === EditAction.Delete) {
                    edit.action = EditAction.Replace;
                }
                // insert and replace edits are all relative to the original state
                // of the document, so inserts should reset the current line/character
                // position to the start.
                line = start.line;
                character = start.character;
                edit.text += diffs[i][1];
                break;

            case dmp.DIFF_EQUAL:
                if (edit !== null) {
                    edits.push(edit);
                    edit = null;
                }
                break;
        }
    }

    if (edit !== null) {
        edits.push(edit);
    }

    return edits;
}