import { diffLines } from '../diff/line.js';

export const INCLUDE_HEADERS = {

includeIndex: true,

includeUnderline: true,

includeFileHeaders: true

};

export const FILE_HEADERS_ONLY = {

includeIndex: false,

includeUnderline: false,

includeFileHeaders: true

};

export const OMIT_HEADERS = {

includeIndex: false,

includeUnderline: false,

includeFileHeaders: false

};

export function structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options) {

let optionsObj;

if (!options) {

optionsObj = {};

}

else if (typeof options === 'function') {

optionsObj = { callback: options };

}

else {

optionsObj = options;

}

if (typeof optionsObj.context === 'undefined') {

optionsObj.context = 4;

}

// We copy this into its own variable to placate TypeScript, which thinks

// optionsObj.context might be undefined in the callbacks below.

const context = optionsObj.context;

// @ts-expect-error (runtime check for something that is correctly a static type error)

if (optionsObj.newlineIsToken) {

throw new Error('newlineIsToken may not be used with patch-generation functions, only with diffing functions');

}

if (!optionsObj.callback) {

return diffLinesResultToPatch(diffLines(oldStr, newStr, optionsObj));

}

else {

const { callback } = optionsObj;

diffLines(oldStr, newStr, Object.assign(Object.assign({}, optionsObj), { callback: (diff) => {

const patch = diffLinesResultToPatch(diff);

// TypeScript is unhappy without the cast because it does not understand that `patch` may

// be undefined here only if `callback` is StructuredPatchCallbackAbortable:

callback(patch);

} }));

}

function diffLinesResultToPatch(diff) {

// STEP 1: Build up the patch with no "\ No newline at end of file" lines and with the arrays

// of lines containing trailing newline characters. We'll tidy up later...

if (!diff) {

return;

}

diff.push({ value: '', lines: [] }); // Append an empty value to make cleanup easier

function contextLines(lines) {

return lines.map(function (entry) { return ' ' + entry; });

}

const hunks = [];

let oldRangeStart = 0, newRangeStart = 0, curRange = [], oldLine = 1, newLine = 1;

for (let i = 0; i < diff.length; i++) {

const current = diff[i], lines = current.lines || splitLines(current.value);

current.lines = lines;

if (current.added || current.removed) {

// If we have previous context, start with that

if (!oldRangeStart) {

const prev = diff[i - 1];

oldRangeStart = oldLine;

newRangeStart = newLine;

if (prev) {

curRange = context > 0 ? contextLines(prev.lines.slice(-context)) : [];

oldRangeStart -= curRange.length;

newRangeStart -= curRange.length;

}

}

// Output our changes

for (const line of lines) {

curRange.push((current.added ? '+' : '-') + line);

}

// Track the updated file position

if (current.added) {

newLine += lines.length;

}

else {

oldLine += lines.length;

}

}

else {

// Identical context lines. Track line changes

if (oldRangeStart) {

// Close out any changes that have been output (or join overlapping)

if (lines.length <= context * 2 && i < diff.length - 2) {

// Overlapping

for (const line of contextLines(lines)) {

curRange.push(line);

}

}

else {

// end the range and output

const contextSize = Math.min(lines.length, context);

for (const line of contextLines(lines.slice(0, contextSize))) {

curRange.push(line);

}

const hunk = {

oldStart: oldRangeStart,

oldLines: (oldLine - oldRangeStart + contextSize),

newStart: newRangeStart,

newLines: (newLine - newRangeStart + contextSize),

lines: curRange

};

hunks.push(hunk);

oldRangeStart = 0;

newRangeStart = 0;

curRange = [];

}

}

oldLine += lines.length;

newLine += lines.length;

}

}

// Step 2: eliminate the trailing `\n` from each line of each hunk, and, where needed, add

// "\ No newline at end of file".

for (const hunk of hunks) {

for (let i = 0; i < hunk.lines.length; i++) {

if (hunk.lines[i].endsWith('\n')) {

hunk.lines[i] = hunk.lines[i].slice(0, -1);

}

else {

hunk.lines.splice(i + 1, 0, '\\ No newline at end of file');

i++; // Skip the line we just added, then continue iterating

}

}

}

return {

oldFileName: oldFileName, newFileName: newFileName,

oldHeader: oldHeader, newHeader: newHeader,

hunks: hunks

};

}

}

/**

* creates a unified diff patch.

* @param patch either a single structured patch object (as returned by `structuredPatch`) or an array of them (as returned by `parsePatch`)

*/

export function formatPatch(patch, headerOptions) {

if (!headerOptions) {

headerOptions = INCLUDE_HEADERS;

}

if (Array.isArray(patch)) {

if (patch.length > 1 && !headerOptions.includeFileHeaders) {

throw new Error('Cannot omit file headers on a multi-file patch. '

+ '(The result would be unparseable; how would a tool trying to apply '

+ 'the patch know which changes are to which file?)');

}

return patch.map(p => formatPatch(p, headerOptions)).join('\n');

}

const ret = [];

if (headerOptions.includeIndex && patch.oldFileName == patch.newFileName) {

ret.push('Index: ' + patch.oldFileName);

}

if (headerOptions.includeUnderline) {

ret.push('===================================================================');

}

if (headerOptions.includeFileHeaders) {

ret.push('--- ' + patch.oldFileName + (typeof patch.oldHeader === 'undefined' ? '' : '\t' + patch.oldHeader));

ret.push('+++ ' + patch.newFileName + (typeof patch.newHeader === 'undefined' ? '' : '\t' + patch.newHeader));

}

for (let i = 0; i < patch.hunks.length; i++) {

const hunk = patch.hunks[i];

// Unified Diff Format quirk: If the chunk size is 0,

// the first number is one lower than one would expect.

// https://www.artima.com/weblogs/viewpost.jsp?thread=164293

if (hunk.oldLines === 0) {

hunk.oldStart -= 1;

}

if (hunk.newLines === 0) {

hunk.newStart -= 1;

}

ret.push('@@ -' + hunk.oldStart + ',' + hunk.oldLines

+ ' +' + hunk.newStart + ',' + hunk.newLines

+ ' @@');

for (const line of hunk.lines) {

ret.push(line);

}

}

return ret.join('\n') + '\n';

}

export function createTwoFilesPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options) {

if (typeof options === 'function') {

options = { callback: options };

}

if (!(options === null || options === void 0 ? void 0 : options.callback)) {

const patchObj = structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options);

if (!patchObj) {

return;

}

return formatPatch(patchObj, options === null || options === void 0 ? void 0 : options.headerOptions);

}

else {

const { callback } = options;

structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, Object.assign(Object.assign({}, options), { callback: patchObj => {

if (!patchObj) {

callback(undefined);

}

else {

callback(formatPatch(patchObj, options.headerOptions));

}

} }));

}

}

export function createPatch(fileName, oldStr, newStr, oldHeader, newHeader, options) {

return createTwoFilesPatch(fileName, fileName, oldStr, newStr, oldHeader, newHeader, options);

}

/**

* Split `text` into an array of lines, including the trailing newline character (where present)

*/

function splitLines(text) {

const hasTrailingNl = text.endsWith('\n');

const result = text.split('\n').map(line => line + '\n');

if (hasTrailingNl) {

result.pop();

}

else {

result.push(result.pop().slice(0, -1));

}

return result;

}