cline/src/integrations/editor/DiffViewProvider.ts

import * as vscode from "vscode"
import * as path from "path"
import * as fs from "fs/promises"
import { createDirectoriesForFile } from "@utils/fs"
import { arePathsEqual } from "@utils/path"
import { formatResponse } from "@core/prompts/responses"
import { DecorationController } from "./DecorationController"
import * as diff from "diff"
import { diagnosticsToProblemsString, getNewDiagnostics } from "../diagnostics"
import { detectEncoding } from "../misc/extract-text"
import * as iconv from "iconv-lite"

export const DIFF_VIEW_URI_SCHEME = "cline-diff"

export class DiffViewProvider {
	editType?: "create" | "modify"
	isEditing = false
	originalContent: string | undefined
	private createdDirs: string[] = []
	private documentWasOpen = false
	private relPath?: string
	private newContent?: string
	private activeDiffEditor?: vscode.TextEditor
	private fadedOverlayController?: DecorationController
	private activeLineController?: DecorationController
	private streamedLines: string[] = []
	private preDiagnostics: [vscode.Uri, vscode.Diagnostic[]][] = []
	private fileEncoding: string = "utf8"
	private lastFirstVisibleLine: number = 0
	private shouldAutoScroll: boolean = true
	private scrollListener?: vscode.Disposable

	constructor(private cwd: string) {}

	async open(relPath: string): Promise<void> {
		this.relPath = relPath
		const fileExists = this.editType === "modify"
		const absolutePath = path.resolve(this.cwd, relPath)
		this.isEditing = true
		this.shouldAutoScroll = true
		this.lastFirstVisibleLine = 0
		// if the file is already open, ensure it's not dirty before getting its contents
		if (fileExists) {
			const existingDocument = vscode.workspace.textDocuments.find((doc) => arePathsEqual(doc.uri.fsPath, absolutePath))
			if (existingDocument && existingDocument.isDirty) {
				await existingDocument.save()
			}
		}

		// get diagnostics before editing the file, we'll compare to diagnostics after editing to see if cline needs to fix anything
		this.preDiagnostics = vscode.languages.getDiagnostics()

		if (fileExists) {
			const fileBuffer = await fs.readFile(absolutePath)
			this.fileEncoding = await detectEncoding(fileBuffer)
			this.originalContent = iconv.decode(fileBuffer, this.fileEncoding)
		} else {
			this.originalContent = ""
			this.fileEncoding = "utf8"
		}
		// for new files, create any necessary directories and keep track of new directories to delete if the user denies the operation
		this.createdDirs = await createDirectoriesForFile(absolutePath)
		// make sure the file exists before we open it
		if (!fileExists) {
			await fs.writeFile(absolutePath, "")
		}
		// if the file was already open, close it (must happen after showing the diff view since if it's the only tab the column will close)
		this.documentWasOpen = false
		// close the tab if it's open (it's already saved above)
		const tabs = vscode.window.tabGroups.all
			.map((tg) => tg.tabs)
			.flat()
			.filter((tab) => tab.input instanceof vscode.TabInputText && arePathsEqual(tab.input.uri.fsPath, absolutePath))
		for (const tab of tabs) {
			if (!tab.isDirty) {
				await vscode.window.tabGroups.close(tab)
			}
			this.documentWasOpen = true
		}
		this.activeDiffEditor = await this.openDiffEditor()
		this.fadedOverlayController = new DecorationController("fadedOverlay", this.activeDiffEditor)
		this.activeLineController = new DecorationController("activeLine", this.activeDiffEditor)
		// Apply faded overlay to all lines initially
		this.fadedOverlayController.addLines(0, this.activeDiffEditor.document.lineCount)
		this.scrollEditorToLine(0) // will this crash for new files?
		this.streamedLines = []

		// Add scroll detection to disable auto-scrolling when user scrolls up
		this.scrollListener = vscode.window.onDidChangeTextEditorVisibleRanges((e: vscode.TextEditorVisibleRangesChangeEvent) => {
			if (e.textEditor === this.activeDiffEditor) {
				const currentFirstVisibleLine = e.visibleRanges[0]?.start.line || 0

				// If the first visible line moved upward, user scrolled up
				// if (currentFirstVisibleLine < this.lastFirstVisibleLine) {
				// 	this.shouldAutoScroll = false
				// }

				// Always update our tracking variable
				this.lastFirstVisibleLine = currentFirstVisibleLine
			}
		})
	}

	async update(
		accumulatedContent: string,
		isFinal: boolean,
		changeLocation?: { startLine: number; endLine: number; startChar: number; endChar: number },
	) {
		if (!this.relPath || !this.activeLineController || !this.fadedOverlayController) {
			throw new Error("Required values not set")
		}

		// --- Fix to prevent duplicate BOM ---
		// Strip potential BOM from incoming content. VS Code's `applyEdit` might implicitly handle the BOM
		// when replacing from the start (0,0), and we want to avoid duplication.
		// Final BOM is handled in `saveChanges`.
		if (accumulatedContent.startsWith("\ufeff")) {
			accumulatedContent = accumulatedContent.slice(1) // Remove the BOM character
		}

		this.newContent = accumulatedContent
		const accumulatedLines = accumulatedContent.split("\n")
		if (!isFinal) {
			accumulatedLines.pop() // remove the last partial line only if it's not the final update
		}
		const diffLines = accumulatedLines.slice(this.streamedLines.length)

		const diffEditor = this.activeDiffEditor
		const document = diffEditor?.document
		if (!diffEditor || !document) {
			throw new Error("User closed text editor, unable to edit file...")
		}

		// Place cursor at the beginning of the diff editor to keep it out of the way of the stream animation
		const beginningOfDocument = new vscode.Position(0, 0)
		diffEditor.selection = new vscode.Selection(beginningOfDocument, beginningOfDocument)

		// Instead of animating each line, we'll update in larger chunks
		const currentLine = this.streamedLines.length + diffLines.length - 1
		if (currentLine >= 0) {
			// Only proceed if we have new lines

			// Replace all content up to the current line with accumulated lines
			// This is necessary (as compared to inserting one line at a time) to handle cases where html tags on previous lines are auto closed for example
			const edit = new vscode.WorkspaceEdit()
			const rangeToReplace = new vscode.Range(0, 0, currentLine + 1, 0)
			const contentToReplace = accumulatedLines.slice(0, currentLine + 1).join("\n") + "\n"
			edit.replace(document.uri, rangeToReplace, contentToReplace)
			await vscode.workspace.applyEdit(edit)

			// Update decorations for the entire changed section
			this.activeLineController.setActiveLine(currentLine)
			this.fadedOverlayController.updateOverlayAfterLine(currentLine, document.lineCount)

			// Scroll to the actual change location if provided, otherwise use the old logic
			if (this.shouldAutoScroll) {
				if (changeLocation) {
					// We have the actual location of the change, scroll to it
					const targetLine = changeLocation.startLine
					this.scrollEditorToLine(targetLine)
				} else {
					// Fallback to the old logic for non-replacement updates
					if (diffLines.length <= 5) {
						// For small changes, just jump directly to the line
						this.scrollEditorToLine(currentLine)
					} else {
						// For larger changes, create a quick scrolling animation
						const startLine = this.streamedLines.length
						const endLine = currentLine
						const totalLines = endLine - startLine
						const numSteps = 10 // Adjust this number to control animation speed
						const stepSize = Math.max(1, Math.floor(totalLines / numSteps))

						// Create and await the smooth scrolling animation
						for (let line = startLine; line <= endLine; line += stepSize) {
							this.activeDiffEditor?.revealRange(
								new vscode.Range(line, 0, line, 0),
								vscode.TextEditorRevealType.InCenter,
							)
							await new Promise((resolve) => setTimeout(resolve, 16)) // ~60fps
						}
						// Ensure we end at the final line
						this.scrollEditorToLine(currentLine)
					}
				}
			}
		}

		// Update the streamedLines with the new accumulated content
		this.streamedLines = accumulatedLines
		if (isFinal) {
			// Handle any remaining lines if the new content is shorter than the original
			if (this.streamedLines.length < document.lineCount) {
				const edit = new vscode.WorkspaceEdit()
				edit.delete(document.uri, new vscode.Range(this.streamedLines.length, 0, document.lineCount, 0))
				await vscode.workspace.applyEdit(edit)
			}
			// Add empty last line if original content had one
			const hasEmptyLastLine = this.originalContent?.endsWith("\n")
			if (hasEmptyLastLine) {
				const accumulatedLines = accumulatedContent.split("\n")
				if (accumulatedLines[accumulatedLines.length - 1] !== "") {
					accumulatedContent += "\n"
				}
			}
			// Clear all decorations at the end (before applying final edit)
			this.fadedOverlayController.clear()
			this.activeLineController.clear()
		}
	}

	async saveChanges(): Promise<{
		newProblemsMessage: string | undefined
		userEdits: string | undefined
		autoFormattingEdits: string | undefined
		finalContent: string | undefined
	}> {
		if (!this.relPath || !this.newContent || !this.activeDiffEditor) {
			return {
				newProblemsMessage: undefined,
				userEdits: undefined,
				autoFormattingEdits: undefined,
				finalContent: undefined,
			}
		}
		const absolutePath = path.resolve(this.cwd, this.relPath)
		const updatedDocument = this.activeDiffEditor.document

		// get the contents before save operation which may do auto-formatting
		const preSaveContent = updatedDocument.getText()

		if (updatedDocument.isDirty) {
			await updatedDocument.save()
		}

		// get text after save in case there is any auto-formatting done by the editor
		const postSaveContent = updatedDocument.getText()

		await vscode.window.showTextDocument(vscode.Uri.file(absolutePath), {
			preview: false,
			preserveFocus: true,
		})
		await this.closeAllDiffViews()

		/*
		Getting diagnostics before and after the file edit is a better approach than
		automatically tracking problems in real-time. This method ensures we only
		report new problems that are a direct result of this specific edit.
		Since these are new problems resulting from Cline's edit, we know they're
		directly related to the work he's doing. This eliminates the risk of Cline
		going off-task or getting distracted by unrelated issues, which was a problem
		with the previous auto-debug approach. Some users' machines may be slow to
		update diagnostics, so this approach provides a good balance between automation
		and avoiding potential issues where Cline might get stuck in loops due to
		outdated problem information. If no new problems show up by the time the user
		accepts the changes, they can always debug later using the '@problems' mention.
		This way, Cline only becomes aware of new problems resulting from his edits
		and can address them accordingly. If problems don't change immediately after
		applying a fix, Cline won't be notified, which is generally fine since the
		initial fix is usually correct and it may just take time for linters to catch up.
		*/
		const postDiagnostics = vscode.languages.getDiagnostics()
		const newProblems = diagnosticsToProblemsString(
			getNewDiagnostics(this.preDiagnostics, postDiagnostics),
			[
				vscode.DiagnosticSeverity.Error, // only including errors since warnings can be distracting (if user wants to fix warnings they can use the @problems mention)
			],
			this.cwd,
		) // will be empty string if no errors
		const newProblemsMessage =
			newProblems.length > 0 ? `\n\nNew problems detected after saving the file:\n${newProblems}` : ""

		// If the edited content has different EOL characters, we don't want to show a diff with all the EOL differences.
		const newContentEOL = this.newContent.includes("\r\n") ? "\r\n" : "\n"
		const normalizedPreSaveContent = preSaveContent.replace(/\r\n|\n/g, newContentEOL).trimEnd() + newContentEOL // trimEnd to fix issue where editor adds in extra new line automatically
		const normalizedPostSaveContent = postSaveContent.replace(/\r\n|\n/g, newContentEOL).trimEnd() + newContentEOL // this is the final content we return to the model to use as the new baseline for future edits
		// just in case the new content has a mix of varying EOL characters
		const normalizedNewContent = this.newContent.replace(/\r\n|\n/g, newContentEOL).trimEnd() + newContentEOL

		let userEdits: string | undefined
		if (normalizedPreSaveContent !== normalizedNewContent) {
			// user made changes before approving edit. let the model know about user made changes (not including post-save auto-formatting changes)
			userEdits = formatResponse.createPrettyPatch(this.relPath.toPosix(), normalizedNewContent, normalizedPreSaveContent)
			// return { newProblemsMessage, userEdits, finalContent: normalizedPostSaveContent }
		} else {
			// no changes to cline's edits
			// return { newProblemsMessage, userEdits: undefined, finalContent: normalizedPostSaveContent }
		}

		let autoFormattingEdits: string | undefined
		if (normalizedPreSaveContent !== normalizedPostSaveContent) {
			// auto-formatting was done by the editor
			autoFormattingEdits = formatResponse.createPrettyPatch(
				this.relPath.toPosix(),
				normalizedPreSaveContent,
				normalizedPostSaveContent,
			)
		}

		return {
			newProblemsMessage,
			userEdits,
			autoFormattingEdits,
			finalContent: normalizedPostSaveContent,
		}
	}

	async revertChanges(): Promise<void> {
		if (!this.relPath || !this.activeDiffEditor) {
			return
		}
		const fileExists = this.editType === "modify"
		const updatedDocument = this.activeDiffEditor.document
		const absolutePath = path.resolve(this.cwd, this.relPath)
		if (!fileExists) {
			if (updatedDocument.isDirty) {
				await updatedDocument.save()
			}
			await this.closeAllDiffViews()
			await fs.unlink(absolutePath)
			// Remove only the directories we created, in reverse order
			for (let i = this.createdDirs.length - 1; i >= 0; i--) {
				await fs.rmdir(this.createdDirs[i])
				console.log(`Directory ${this.createdDirs[i]} has been deleted.`)
			}
			console.log(`File ${absolutePath} has been deleted.`)
		} else {
			// revert document
			const edit = new vscode.WorkspaceEdit()
			const fullRange = new vscode.Range(
				updatedDocument.positionAt(0),
				updatedDocument.positionAt(updatedDocument.getText().length),
			)
			edit.replace(updatedDocument.uri, fullRange, this.originalContent ?? "")
			// Apply the edit and save, since contents shouldn't have changed this won't show in local history unless of course the user made changes and saved during the edit
			await vscode.workspace.applyEdit(edit)
			await updatedDocument.save()
			console.log(`File ${absolutePath} has been reverted to its original content.`)
			if (this.documentWasOpen) {
				await vscode.window.showTextDocument(vscode.Uri.file(absolutePath), {
					preview: false,
					preserveFocus: true,
				})
			}
			await this.closeAllDiffViews()
		}

		// edit is done
		await this.reset()
	}

	private async closeAllDiffViews() {
		const tabs = vscode.window.tabGroups.all
			.flatMap((tg) => tg.tabs)
			.filter((tab) => tab.input instanceof vscode.TabInputTextDiff && tab.input?.original?.scheme === DIFF_VIEW_URI_SCHEME)
		for (const tab of tabs) {
			// trying to close dirty views results in save popup
			if (!tab.isDirty) {
				await vscode.window.tabGroups.close(tab)
			}
		}
	}

	private async openDiffEditor(): Promise<vscode.TextEditor> {
		if (!this.relPath) {
			throw new Error("No file path set")
		}
		const uri = vscode.Uri.file(path.resolve(this.cwd, this.relPath))
		// If this diff editor is already open (ie if a previous write file was interrupted) then we should activate that instead of opening a new diff
		const diffTab = vscode.window.tabGroups.all
			.flatMap((group) => group.tabs)
			.find(
				(tab) =>
					tab.input instanceof vscode.TabInputTextDiff &&
					tab.input?.original?.scheme === DIFF_VIEW_URI_SCHEME &&
					arePathsEqual(tab.input.modified.fsPath, uri.fsPath),
			)
		if (diffTab && diffTab.input instanceof vscode.TabInputTextDiff) {
			const editor = await vscode.window.showTextDocument(diffTab.input.modified, {
				preserveFocus: true,
			})
			return editor
		}
		// Open new diff editor
		return new Promise<vscode.TextEditor>((resolve, reject) => {
			const fileName = path.basename(uri.fsPath)
			const fileExists = this.editType === "modify"
			const disposable = vscode.window.onDidChangeActiveTextEditor((editor) => {
				if (editor && arePathsEqual(editor.document.uri.fsPath, uri.fsPath)) {
					disposable.dispose()
					resolve(editor)
				}
			})
			vscode.commands.executeCommand(
				"vscode.diff",
				vscode.Uri.parse(`${DIFF_VIEW_URI_SCHEME}:${fileName}`).with({
					query: Buffer.from(this.originalContent ?? "").toString("base64"),
				}),
				uri,
				`${fileName}: ${fileExists ? "Original ↔ Cline's Changes" : "New File"} (Editable)`,
				{
					preserveFocus: true,
				},
			)
			// This may happen on very slow machines ie project idx
			setTimeout(() => {
				disposable.dispose()
				reject(new Error("Failed to open diff editor, please try again..."))
			}, 10_000)
		})
	}

	private scrollEditorToLine(line: number) {
		if (this.activeDiffEditor) {
			const scrollLine = line + 4
			this.activeDiffEditor.revealRange(
				new vscode.Range(scrollLine, 0, scrollLine, 0),
				vscode.TextEditorRevealType.InCenter,
			)
		}
	}

	scrollToFirstDiff() {
		if (!this.activeDiffEditor) {
			return
		}
		const currentContent = this.activeDiffEditor.document.getText()
		const diffs = diff.diffLines(this.originalContent || "", currentContent)
		let lineCount = 0
		for (const part of diffs) {
			if (part.added || part.removed) {
				// Found the first diff, scroll to it
				this.activeDiffEditor.revealRange(
					new vscode.Range(lineCount, 0, lineCount, 0),
					vscode.TextEditorRevealType.InCenter,
				)
				return
			}
			if (!part.removed) {
				lineCount += part.count || 0
			}
		}
	}

	// close editor if open?
	async reset() {
		this.editType = undefined
		this.isEditing = false
		this.originalContent = undefined
		this.createdDirs = []
		this.documentWasOpen = false
		this.activeDiffEditor = undefined
		this.fadedOverlayController = undefined
		this.activeLineController = undefined
		this.streamedLines = []
		this.preDiagnostics = []

		// Clean up the scroll listener
		if (this.scrollListener) {
			this.scrollListener.dispose()
			this.scrollListener = undefined
		}

		// Reset auto-scroll state
		this.shouldAutoScroll = true
		this.lastFirstVisibleLine = 0
	}
}