import { dirname, join } from "node:path"
import { existsSync } from "node:fs"
import { writeFile } from "node:fs/promises"
import { $ } from "bun"
import {
  type RegimeConfig,
  findRegimeConfigs,
  resolveTemplateChain,
  getStrategy,
  interpolate,
  deinterpolate,
  readFileSync,
  templatesDir,
} from "./shared"

const green = Bun.color("green", "ansi")
const orange = Bun.color("orange", "ansi")
const purple = Bun.color("purple", "ansi")
const reset = "\x1b[0m"

async function gumStdin(command: string, input: string): Promise<string> {
  const proc = Bun.spawn(["gum", command], {
    stdin: Buffer.from(input),
    stdout: "pipe",
    stderr: "inherit",
  })
  const output = await new Response(proc.stdout).text()
  await proc.exited
  return output
}

interface PromotableFile {
  relPath: string       // relative path within template/repo (e.g. "tsconfig.json")
  repoPath: string      // absolute path in the repo
  configDir: string     // directory containing regime.config.json
  vars: Record<string, string>
  templateNames: string[] // all templates in the inheritance tree
}

export async function promote(targetDir: string, yes = false): Promise<void> {
  // Step 1: Find regime configs
  const rcFiles = await findRegimeConfigs(targetDir)
  if (rcFiles.length === 0) {
    console.error("No regime.config.json files found.")
    process.exit(1)
  }

  // Step 2: Collect promotable files (overwrite-strategy files that differ)
  const promotable: PromotableFile[] = []

  for (const rcFile of rcFiles) {
    const rcDir = dirname(rcFile)
    const rc: RegimeConfig = JSON.parse(readFileSync(rcFile))
    const templateNames = Array.isArray(rc.templates) ? rc.templates : [rc.templates]
    const vars = rc.vars ?? {}

    const { files, patterns, templateNames: chainNames } = resolveTemplateChain(templateNames)

    for (const [relPath, templatePaths] of files) {
      const strategy = getStrategy(relPath, patterns)
      if (strategy !== "overwrite") continue

      const repoPath = join(rcDir, relPath)
      if (!existsSync(repoPath)) continue

      const repoContent = readFileSync(repoPath)
      const templateContent = interpolate(
        readFileSync(templatePaths[templatePaths.length - 1]),
        vars,
        relPath,
      )

      if (repoContent !== templateContent) {
        promotable.push({
          relPath,
          repoPath,
          configDir: rcDir,
          vars,
          templateNames: chainNames,
        })
      }
    }
  }

  if (promotable.length === 0) {
    console.log("Nothing to promote.")
    return
  }

  // Step 3: Interactive file selection via gum filter
  const fileList = promotable.map(p => p.relPath).join("\n")
  const selectedFile = (await gumStdin("filter", fileList)).trim()

  if (!selectedFile) {
    console.log("No file selected.")
    return
  }

  const entry = promotable.find(p => p.relPath === selectedFile)
  if (!entry) {
    console.error(`File "${selectedFile}" not found in promotable list.`)
    process.exit(1)
  }

  // Step 4: Interactive template selection via gum choose
  let selectedTemplate: string
  if (entry.templateNames.length === 1) {
    selectedTemplate = entry.templateNames[0]
  } else {
    const templateList = entry.templateNames.join("\n")
    selectedTemplate = (await gumStdin("choose", templateList)).trim()
  }

  if (!selectedTemplate) {
    console.log("No template selected.")
    return
  }

  // Step 5: De-interpolate
  const repoContent = readFileSync(entry.repoPath)
  const promoted = deinterpolate(repoContent, entry.vars)

  // Step 6: Show diff
  const templateFilePath = join(templatesDir, selectedTemplate, entry.relPath)

  console.log(`\n${purple}Promoting${reset} ${entry.relPath} -> ${green}${selectedTemplate}${reset}`)

  if (existsSync(templateFilePath)) {
    const tmpFile = `/tmp/regime-promote-${Date.now()}`
    await writeFile(tmpFile, promoted)
    try {
      const diff = await $`diff -u ${templateFilePath} ${tmpFile} || true`.text()
      if (diff.trim()) {
        console.log(diff)
      } else {
        console.log("No changes detected after de-interpolation.")
        return
      }
    } finally {
      await $`rm -f ${tmpFile}`.quiet()
    }
  } else {
    console.log(`${orange}New file${reset} — will be created in template "${selectedTemplate}"`)
    console.log(promoted)
  }

  // Step 7: Confirm
  if (!yes) {
    const confirmed = await $`gum confirm "Write to template?"`.nothrow()
    if (confirmed.exitCode !== 0) {
      console.log("Cancelled.")
      return
    }
  }

  // Step 8: Write
  const targetFileDir = dirname(templateFilePath)
  if (!existsSync(targetFileDir)) {
    await $`mkdir -p ${targetFileDir}`.quiet()
  }
  await writeFile(templateFilePath, promoted)
  console.log(`${green}Written${reset} ${templateFilePath}`)
}