import { promises as fs } from "fs"
import { join } from "path"
import { resolveSymlinkAsync, isMarkdownFile } from "../../shared/file-utils"
import type { LoadedSkill, SkillScope } from "./types"
import { inferSkillNameFromFileName, loadSkillFromPath } from "./loaded-skill-from-path"

export async function loadSkillsFromDir(options: {
  skillsDir: string
  scope: SkillScope
  namePrefix?: string
  depth?: number
  maxDepth?: number
}): Promise<LoadedSkill[]> {
  const namePrefix = options.namePrefix ?? ""
  const depth = options.depth ?? 0
  const maxDepth = options.maxDepth ?? 2

  const entries = await fs.readdir(options.skillsDir, { withFileTypes: true }).catch(() => [])
  const skillMap = new Map<string, LoadedSkill>()

  const directories = entries.filter(
    (entry) => !entry.name.startsWith(".") && (entry.isDirectory() || entry.isSymbolicLink())
  )
  const files = entries.filter(
    (entry) =>
      !entry.name.startsWith(".") &&
      !entry.isDirectory() &&
      !entry.isSymbolicLink() &&
      isMarkdownFile(entry)
  )

  for (const entry of directories) {
    const entryPath = join(options.skillsDir, entry.name)
    const resolvedPath = await resolveSymlinkAsync(entryPath)
    const dirName = entry.name

    const skillMdPath = join(resolvedPath, "SKILL.md")
    try {
      await fs.access(skillMdPath)
      const skill = await loadSkillFromPath({
        skillPath: skillMdPath,
        resolvedPath,
        defaultName: dirName,
        scope: options.scope,
        namePrefix,
      })
      if (skill && !skillMap.has(skill.name)) {
        skillMap.set(skill.name, skill)
      }
      continue
    } catch {
      // no SKILL.md
    }

    const namedSkillMdPath = join(resolvedPath, `${dirName}.md`)
    try {
      await fs.access(namedSkillMdPath)
      const skill = await loadSkillFromPath({
        skillPath: namedSkillMdPath,
        resolvedPath,
        defaultName: dirName,
        scope: options.scope,
        namePrefix,
      })
      if (skill && !skillMap.has(skill.name)) {
        skillMap.set(skill.name, skill)
      }
      continue
    } catch {
      // no named md
    }

    if (depth < maxDepth) {
      const newPrefix = namePrefix ? `${namePrefix}/${dirName}` : dirName
      const nestedSkills = await loadSkillsFromDir({
        skillsDir: resolvedPath,
        scope: options.scope,
        namePrefix: newPrefix,
        depth: depth + 1,
        maxDepth,
      })
      for (const nestedSkill of nestedSkills) {
        if (!skillMap.has(nestedSkill.name)) {
          skillMap.set(nestedSkill.name, nestedSkill)
        }
      }
    }
  }

  for (const entry of files) {
    const entryPath = join(options.skillsDir, entry.name)
    const baseName = inferSkillNameFromFileName(entryPath)
    const skill = await loadSkillFromPath({
      skillPath: entryPath,
      resolvedPath: options.skillsDir,
      defaultName: baseName,
      scope: options.scope,
      namePrefix,
    })
    if (skill && !skillMap.has(skill.name)) {
      skillMap.set(skill.name, skill)
    }
  }

  return Array.from(skillMap.values())
}