import { dirname, relative, join } from "node:path"
import { existsSync } from "node:fs"
import {
  type RegimeConfig,
  findRegimeConfigs,
  resolveTemplateChain,
  getStrategy,
  interpolate,
  readFileSync,
  diffJson,
  mergeTemplateJsonFiles,
} from "./shared"

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

export async function check(targetDir: string): Promise<void> {
  const rcFiles = await findRegimeConfigs(targetDir)

  if (rcFiles.length === 0) {
    console.log("No regime.config.json files found.")
    return
  }

  for (const rcFile of rcFiles) {
    const rcDir = dirname(rcFile)
    const relDir = relative(targetDir, rcDir) || "."
    console.log(`\n${purple}${relDir}/${reset}`)

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

    const { files, patterns } = resolveTemplateChain(templateNames)

    if (files.size === 0) {
      console.log("  (no template files)")
      continue
    }

    let synced = true

    for (const [relPath, templatePaths] of files) {
      const targetPath = join(rcDir, relPath)
      const strategy = getStrategy(relPath, patterns)

      if (!existsSync(targetPath)) {
        console.log(`  ${relPath}: ${red}missing${reset}`)
        synced = false
        continue
      }

      const existingContent = readFileSync(targetPath)

      if (strategy === "merge json") {
        try {
          const templateObj = mergeTemplateJsonFiles(templatePaths, vars, relPath)
          const existingObj = JSON.parse(existingContent)
          const diffs = diffJson(templateObj, existingObj)

          if (diffs.length > 0) {
            synced = false
            console.log(`  ${relPath}:`)
            for (const d of diffs) {
              const exp = JSON.stringify(d.expected)
              const act = d.actual === undefined ? `${red}missing${reset}` : `${orange}${JSON.stringify(d.actual)}${reset}`
              console.log(`    ${d.field}: ${act} -> ${green}${exp}${reset}`)
            }
          }
        } catch (e) {
          console.log(`  ${relPath}: ${red}failed to parse JSON${reset} - ${e}`)
          synced = false
        }
      } else if (strategy === "overwrite") {
        const templateContent = interpolate(readFileSync(templatePaths[templatePaths.length - 1]), vars, relPath)
        if (existingContent !== templateContent) {
          console.log(`  ${relPath}: ${orange}differs${reset}`)
          synced = false
        }
      }
    }

    if (synced) {
      console.log(`  ${green}in sync${reset}`)
    }
  }
}