180 lines · 5.3 KB
| 1 | /** |
| 2 | * Diff service: compute file-level and line-level diffs between commits. |
| 3 | */ |
| 4 | |
| 5 | import { parseTree, parseCommit, type TreeEntry } from '@gitfastr/shared'; |
| 6 | import { computeDiff, type DiffHunk } from '@gitfastr/shared/git/diff.js'; |
| 7 | import { ObjectStore } from './object-store.js'; |
| 8 | |
| 9 | const decoder = new TextDecoder(); |
| 10 | |
| 11 | export type FileChangeStatus = 'added' | 'deleted' | 'modified'; |
| 12 | |
| 13 | export interface FileDiff { |
| 14 | path: string; |
| 15 | status: FileChangeStatus; |
| 16 | oldSha: string | null; |
| 17 | newSha: string | null; |
| 18 | hunks: DiffHunk[]; |
| 19 | isBinary: boolean; |
| 20 | } |
| 21 | |
| 22 | export class DiffService { |
| 23 | constructor(private objectStore: ObjectStore) {} |
| 24 | |
| 25 | /** |
| 26 | * Compute diffs between two commits. |
| 27 | * Returns a list of changed files with their line-level diffs. |
| 28 | */ |
| 29 | async diffCommits(oldCommitSha: string, newCommitSha: string): Promise<FileDiff[]> { |
| 30 | const [oldCommit, newCommit] = await Promise.all([ |
| 31 | this.getCommitTree(oldCommitSha), |
| 32 | this.getCommitTree(newCommitSha), |
| 33 | ]); |
| 34 | |
| 35 | return this.diffTrees(oldCommit, newCommit, ''); |
| 36 | } |
| 37 | |
| 38 | /** |
| 39 | * Compute diff for a single commit against its first parent. |
| 40 | * For root commits, diff against empty tree. |
| 41 | */ |
| 42 | async diffCommitAgainstParent(commitSha: string): Promise<FileDiff[]> { |
| 43 | const obj = await this.objectStore.get(commitSha); |
| 44 | if (!obj || obj.type !== 'commit') return []; |
| 45 | |
| 46 | const commit = parseCommit(obj.content); |
| 47 | const newTreeSha = commit.tree; |
| 48 | |
| 49 | if (commit.parents.length === 0) { |
| 50 | // Root commit — diff against empty tree |
| 51 | return this.diffTrees(new Map(), await this.flattenTree(newTreeSha, ''), ''); |
| 52 | } |
| 53 | |
| 54 | const parentObj = await this.objectStore.get(commit.parents[0]); |
| 55 | if (!parentObj || parentObj.type !== 'commit') return []; |
| 56 | const parentCommit = parseCommit(parentObj.content); |
| 57 | |
| 58 | const [oldTree, newTree] = await Promise.all([ |
| 59 | this.flattenTree(parentCommit.tree, ''), |
| 60 | this.flattenTree(newTreeSha, ''), |
| 61 | ]); |
| 62 | |
| 63 | return this.diffTrees(oldTree, newTree, ''); |
| 64 | } |
| 65 | |
| 66 | private async getCommitTree(commitSha: string): Promise<Map<string, { sha: string; mode: string }>> { |
| 67 | const obj = await this.objectStore.get(commitSha); |
| 68 | if (!obj || obj.type !== 'commit') return new Map(); |
| 69 | const commit = parseCommit(obj.content); |
| 70 | return this.flattenTree(commit.tree, ''); |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * Flatten a tree into a map of path -> {sha, mode}. |
| 75 | * Recursively walks subtrees. |
| 76 | */ |
| 77 | private async flattenTree( |
| 78 | treeSha: string, |
| 79 | prefix: string |
| 80 | ): Promise<Map<string, { sha: string; mode: string }>> { |
| 81 | const result = new Map<string, { sha: string; mode: string }>(); |
| 82 | const obj = await this.objectStore.get(treeSha); |
| 83 | if (!obj || obj.type !== 'tree') return result; |
| 84 | |
| 85 | const entries = parseTree(obj.content); |
| 86 | for (const entry of entries) { |
| 87 | const fullPath = prefix ? `${prefix}/${entry.name}` : entry.name; |
| 88 | if (entry.mode === '40000' || entry.mode === '040000') { |
| 89 | // Recurse into subtree |
| 90 | const subTree = await this.flattenTree(entry.sha, fullPath); |
| 91 | for (const [path, info] of subTree) { |
| 92 | result.set(path, info); |
| 93 | } |
| 94 | } else { |
| 95 | result.set(fullPath, { sha: entry.sha, mode: entry.mode }); |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | return result; |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Compare two flattened trees and produce file diffs. |
| 104 | */ |
| 105 | private async diffTrees( |
| 106 | oldTree: Map<string, { sha: string; mode: string }>, |
| 107 | newTree: Map<string, { sha: string; mode: string }>, |
| 108 | _prefix: string |
| 109 | ): Promise<FileDiff[]> { |
| 110 | const allPaths = new Set([...oldTree.keys(), ...newTree.keys()]); |
| 111 | const diffs: FileDiff[] = []; |
| 112 | |
| 113 | for (const path of [...allPaths].sort()) { |
| 114 | const oldEntry = oldTree.get(path); |
| 115 | const newEntry = newTree.get(path); |
| 116 | |
| 117 | if (!oldEntry && newEntry) { |
| 118 | // Added |
| 119 | const diff = await this.makeFileDiff(path, 'added', null, newEntry.sha); |
| 120 | diffs.push(diff); |
| 121 | } else if (oldEntry && !newEntry) { |
| 122 | // Deleted |
| 123 | const diff = await this.makeFileDiff(path, 'deleted', oldEntry.sha, null); |
| 124 | diffs.push(diff); |
| 125 | } else if (oldEntry && newEntry && oldEntry.sha !== newEntry.sha) { |
| 126 | // Modified |
| 127 | const diff = await this.makeFileDiff(path, 'modified', oldEntry.sha, newEntry.sha); |
| 128 | diffs.push(diff); |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | return diffs; |
| 133 | } |
| 134 | |
| 135 | private async makeFileDiff( |
| 136 | path: string, |
| 137 | status: FileChangeStatus, |
| 138 | oldSha: string | null, |
| 139 | newSha: string | null |
| 140 | ): Promise<FileDiff> { |
| 141 | let oldContent = ''; |
| 142 | let newContent = ''; |
| 143 | let isBinary = false; |
| 144 | |
| 145 | if (oldSha) { |
| 146 | const obj = await this.objectStore.get(oldSha); |
| 147 | if (obj && obj.type === 'blob') { |
| 148 | if (this.isBinaryContent(obj.content)) { |
| 149 | isBinary = true; |
| 150 | } else { |
| 151 | oldContent = decoder.decode(obj.content); |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | if (newSha) { |
| 157 | const obj = await this.objectStore.get(newSha); |
| 158 | if (obj && obj.type === 'blob') { |
| 159 | if (this.isBinaryContent(obj.content)) { |
| 160 | isBinary = true; |
| 161 | } else { |
| 162 | newContent = decoder.decode(obj.content); |
| 163 | } |
| 164 | } |
| 165 | } |
| 166 | |
| 167 | const hunks = isBinary ? [] : computeDiff(oldContent, newContent); |
| 168 | |
| 169 | return { path, status, oldSha, newSha, hunks, isBinary }; |
| 170 | } |
| 171 | |
| 172 | private isBinaryContent(content: Uint8Array): boolean { |
| 173 | const checkLen = Math.min(content.length, 8000); |
| 174 | for (let i = 0; i < checkLen; i++) { |
| 175 | if (content[i] === 0) return true; |
| 176 | } |
| 177 | return false; |
| 178 | } |
| 179 | } |
| 180 |