full template restoreablity

reverse.ts

@@ -8,7 +8,7 @@ import {
 } from "node:fs"
 import { dirname, isAbsolute, relative, resolve as resolvePath } from "node:path"
 import { TextDecoder } from "node:util"
-import type { ReverseMapFile, ReverseMapManifest, ReverseMapToken } from "./render"
+import type { ReverseMapFile, ReverseMapManifest, ReverseMapStoredTemplate, ReverseMapToken } from "./render"
 
 export type ReverseOptions = {
   mapPath?: string
@@ -71,17 +71,73 @@ function replaceFirst(content: string, token: ReverseMapToken): string | null {
   return `${content.slice(0, index)}${token.token}${content.slice(index + token.result.length)}`
 }
 
+function applyActiveBranch(token: ReverseMapToken, branchContent: string): string {
+  if (!token.activeRange) return token.token
+  return [
+    token.token.slice(0, token.activeRange.start),
+    branchContent,
+    token.token.slice(token.activeRange.end),
+  ].join("")
+}
+
+function findPrefixEnd(content: string, before: string): number {
+  if (before === "") return 0
+  let candidate = before
+  while (candidate.length >= 8) {
+    const index = content.indexOf(candidate)
+    if (index !== -1) return index + candidate.length
+    candidate = candidate.slice(-Math.max(1, Math.floor(candidate.length / 2)))
+  }
+  return -1
+}
+
+function findSuffixStart(content: string, after: string, from: number): number {
+  if (after === "") return content.length
+  let candidate = after
+  while (candidate.length >= 8) {
+    const index = content.indexOf(candidate, from)
+    if (index !== -1) return index
+    candidate = candidate.slice(0, Math.floor(candidate.length / 2))
+  }
+  return -1
+}
+
+function replaceConditional(content: string, token: ReverseMapToken): string | null {
+  const exactIndex = content.indexOf(token.result)
+  if (exactIndex !== -1) {
+    return [
+      content.slice(0, exactIndex),
+      token.token,
+      content.slice(exactIndex + token.result.length),
+    ].join("")
+  }
+
+  if (token.before === undefined || token.after === undefined) return null
+
+  const branchStart = findPrefixEnd(content, token.before)
+  if (branchStart === -1) return null
+
+  const afterIndex = findSuffixStart(content, token.after, branchStart)
+  if (afterIndex === -1) return null
+
+  return [
+    content.slice(0, branchStart),
+    applyActiveBranch(token, content.slice(branchStart, afterIndex)),
+    content.slice(afterIndex),
+  ].join("")
+}
+
 function reverseContent(
   content: string,
   file: ReverseMapFile,
   warnings: ReverseWarning[],
 ): string {
-  const tokens = file.tokens
+  const contentTokens = file.tokens
     .filter(token => token.kind === "content")
     .sort((a, b) => (b.range?.start ?? -1) - (a.range?.start ?? -1))
 
   let reversed = content
-  for (const token of tokens) {
+  for (const token of contentTokens) {
     const rangeResult = replaceAtRange(reversed, token)
     if (rangeResult !== null) {
       reversed = rangeResult
@@ -101,9 +157,47 @@ function reverseContent(
       message: "Rendered value was not found; token was not restored",
     })
   }
+
+  const conditionalTokens = file.tokens
+    .filter(token => token.kind === "conditional")
+    .sort((a, b) => (b.range?.start ?? -1) - (a.range?.start ?? -1))
+
+  for (const token of conditionalTokens) {
+    const result = replaceConditional(reversed, token)
+    if (result !== null) {
+      reversed = result
+      continue
+    }
+
+    warnings.push({
+      outputPath: file.outputPath,
+      token: token.token,
+      result: token.result,
+      message: "Rendered conditional block was not found; block was not restored",
+    })
+  }
+
   return reversed
 }
 
+function writeSkippedTemplate(
+  templateRoot: string,
+  skipped: ReverseMapStoredTemplate,
+): number {
+  const templatePath = resolveInside(templateRoot, skipped.templatePath)
+  if (skipped.kind === "directory") {
+    mkdirSync(templatePath, { recursive: true })
+    return 0
+  }
+
+  mkdirSync(dirname(templatePath), { recursive: true })
+  const content = skipped.encoding === "base64"
+    ? Buffer.from(skipped.content ?? "", "base64")
+    : skipped.content ?? ""
+  writeFileSync(templatePath, content)
+  return 1
+}
+
 export function reverseDir(
   renderedDir: string,
   templateDir: string,
@@ -154,5 +248,9 @@ export function reverseDir(
     filesWritten += 1
   }
 
+  for (const skipped of manifest.skipped ?? []) {
+    filesWritten += writeSkippedTemplate(templateRoot, skipped)
+  }
+
   return { filesWritten, warnings }
 }