import { existsSync } from 'node:fs'
import { readdir, rename, readFile, writeFile, unlink } from 'node:fs/promises'
import { dirname, join, resolve, normalize, isAbsolute } from 'node:path'
import { pathToFileURL, fileURLToPath } from 'node:url'
import {
  app,
  BrowserWindow,
  dialog,
  ipcMain,
  Menu,
  nativeImage,
  shell,
  type MenuItemConstructorOptions,
  type NativeImage
} from 'electron'
import type {
  DirEntry,
  ListDirResult,
  OpenFileResult,
  OpenFolderResult,
  OpenImageResult,
  SaveDialogResult
} from './ipc-types.js'

const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)

const MD_EXT = new Set(['.md', '.markdown', '.mdown', '.mkd'])

function getPreloadPath(): string {
  const fromMainDir = join(__dirname, '..', 'preload')
  const fromAppRoot = join(app.getAppPath(), 'out', 'preload')
  const candidates = ['index.mjs', 'index.cjs', 'index.js']
  for (const base of [fromMainDir, fromAppRoot]) {
    for (const name of candidates) {
      const p = resolve(base, name)
      if (existsSync(p)) return p
    }
  }
  return resolve(fromAppRoot, 'index.mjs')
}

function getRendererIndexHtml(): string {
  const fromMain = join(__dirname, '..', 'renderer', 'index.html')
  if (existsSync(fromMain)) return fromMain
  return join(app.getAppPath(), 'out', 'renderer', 'index.html')
}

function resolveAppIconPath(): string | undefined {
  const candidates = [
    join(__dirname, '../../resources/app-icon.png'),
    join(app.getAppPath(), 'resources', 'app-icon.png'),
    join(process.cwd(), 'resources', 'app-icon.png')
  ]
  for (const p of candidates) {
    if (existsSync(p)) return p
  }
  return undefined
}

function isMarkdownFile(name: string): boolean {
  const lower = name.toLowerCase()
  const dot = lower.lastIndexOf('.')
  if (dot < 0) return false
  return MD_EXT.has(lower.slice(dot))
}

/** 将 Markdown 内链（相对/绝对/file://）解析为本地绝对路径；外链原样返回。 */
function resolveMarkdownLinkHref(baseFilePath: string, href: string): string {
  let raw = href.trim()
  const hashIdx = raw.indexOf('#')
  if (hashIdx >= 0) raw = raw.slice(0, hashIdx)
  const queryIdx = raw.indexOf('?')
  if (queryIdx >= 0) raw = raw.slice(0, queryIdx)
  raw = raw.trim()
  if (!raw) return ''
  if (/^https?:\/\//i.test(raw) || /^mailto:/i.test(raw) || /^tel:/i.test(raw)) return raw
  if (raw.startsWith('file://')) {
    try {
      return normalize(fileURLToPath(raw))
    } catch {
      return ''
    }
  }
  let decoded = raw
  try {
    decoded = decodeURIComponent(raw)
  } catch {
    decoded = raw
  }
  if (isAbsolute(decoded)) return normalize(decoded)
  return normalize(resolve(dirname(baseFilePath), decoded))
}

ipcMain.handle(
  'myreader:resolve-relative-path',
  (_evt, baseFilePath: string, href: string): string => {
    if (typeof baseFilePath !== 'string' || typeof href !== 'string') return ''
    if (!baseFilePath.trim()) return ''
    return resolveMarkdownLinkHref(baseFilePath, href)
  }
)

ipcMain.handle('myreader:open-external', async (_evt, url: string): Promise<void> => {
  if (typeof url !== 'string') return
  const u = url.trim()
  if (/^https?:\/\//i.test(u) || /^mailto:/i.test(u) || /^tel:/i.test(u)) {
    await shell.openExternal(u)
  }
})

async function listDirectoryImpl(dirPath: string): Promise<ListDirResult> {
  const normalized = normalize(dirPath)
  try {
    const dirents = await readdir(normalized, { withFileTypes: true })
    const entries: DirEntry[] = []
    for (const d of dirents) {
      if (d.name.startsWith('.')) continue
      const full = join(normalized, d.name)
      if (d.isDirectory()) {
        entries.push({ name: d.name, path: full, kind: 'dir' })
      } else if (d.isFile() && isMarkdownFile(d.name)) {
        entries.push({ name: d.name, path: full, kind: 'file' })
      }
    }
    entries.sort((a, b) => {
      if (a.kind !== b.kind) return a.kind === 'dir' ? -1 : 1
      return a.name.localeCompare(b.name, undefined, { sensitivity: 'base' })
    })
    return { entries }
  } catch (e) {
    const msg = e instanceof Error ? e.message : String(e)
    return { entries: [], error: msg }
  }
}

function sendMenu(win: BrowserWindow | null, action: string): void {
  const w = win ?? BrowserWindow.getFocusedWindow()
  w?.webContents.send('myreader:menu', action)
}

function buildMenu(): Menu {
  const template: MenuItemConstructorOptions[] = [
    {
      label: '文件',
      submenu: [
        { label: '新建标签', accelerator: 'CmdOrCtrl+T', click: () => sendMenu(null, 'tab-new') },
        { label: '打开…', accelerator: 'CmdOrCtrl+O', click: () => sendMenu(null, 'file-open') },
        { label: '保存', accelerator: 'CmdOrCtrl+S', click: () => sendMenu(null, 'file-save') },
        { label: '另存为…', accelerator: 'CmdOrCtrl+Shift+S', click: () => sendMenu(null, 'file-save-as') },
        { type: 'separator' },
        { label: '关闭标签', accelerator: 'CmdOrCtrl+W', click: () => sendMenu(null, 'tab-close') },
        { type: 'separator' },
        { label: '退出', accelerator: process.platform === 'darwin' ? 'Cmd+Q' : 'Alt+F4', role: 'quit' }
      ]
    },
    {
      label: '编辑',
      submenu: [
        { label: '撤销', accelerator: 'CmdOrCtrl+Z', role: 'undo' },
        { label: '重做', accelerator: process.platform === 'darwin' ? 'Cmd+Shift+Z' : 'Ctrl+Y', role: 'redo' },
        { type: 'separator' },
        { label: '剪切', accelerator: 'CmdOrCtrl+X', role: 'cut' },
        { label: '复制', accelerator: 'CmdOrCtrl+C', role: 'copy' },
        { label: '粘贴', accelerator: 'CmdOrCtrl+V', role: 'paste' },
        { label: '全选', accelerator: 'CmdOrCtrl+A', role: 'selectAll' }
      ]
    },
    {
      label: '视图',
      submenu: [
        { label: '切换视图模式', accelerator: 'CmdOrCtrl+E', click: () => sendMenu(null, 'toggle-read') },
        { label: '下一个标签', accelerator: 'Ctrl+Tab', click: () => sendMenu(null, 'tab-next') },
        { label: '上一个标签', accelerator: 'Ctrl+Shift+Tab', click: () => sendMenu(null, 'tab-prev') }
      ]
    },
    {
      label: '帮助',
      submenu: [{ label: "关于 Huangzhijun's Reader", click: () => sendMenu(null, 'help-about') }]
    }
  ]
  return Menu.buildFromTemplate(template)
}

function createWindow(): BrowserWindow {
  const preloadPath = getPreloadPath()
  const iconPath = resolveAppIconPath()
  let icon: NativeImage | undefined
  if (iconPath) {
    try {
      icon = nativeImage.createFromPath(iconPath)
      if (icon.isEmpty()) icon = undefined
    } catch {
      icon = undefined
    }
  }
  const win = new BrowserWindow({
    width: 1200,
    height: 800,
    minWidth: 800,
    minHeight: 560,
    title: "Huangzhijun's Reader",
    ...(icon ? { icon } : {}),
    webPreferences: {
      preload: preloadPath,
      contextIsolation: true,
      sandbox: false,
      nodeIntegration: false,
      webSecurity: false
    }
  })

  win.on('close', (e) => {
    const w = win as BrowserWindow & { __myreaderForceClose?: boolean }
    if (w.__myreaderForceClose) return
    e.preventDefault()
    win.webContents.send('myreader:request-close')
  })

  if (process.env.ELECTRON_RENDERER_URL) {
    void win.loadURL(process.env.ELECTRON_RENDERER_URL)
  } else {
    void win.loadFile(getRendererIndexHtml())
  }
  return win
}

ipcMain.handle('myreader:open-file-dialog', async (): Promise<OpenFileResult> => {
  const win = BrowserWindow.getFocusedWindow()
  const { canceled, filePaths } = win
    ? await dialog.showOpenDialog(win, {
        properties: ['openFile'],
        filters: [{ name: 'Markdown', extensions: ['md', 'markdown', 'mdown', 'mkd', 'txt'] }]
      })
    : await dialog.showOpenDialog({
        properties: ['openFile'],
        filters: [{ name: 'Markdown', extensions: ['md', 'markdown', 'mdown', 'mkd', 'txt'] }]
      })
  if (canceled || !filePaths?.[0]) return { canceled: true }
  const path = filePaths[0]
  const content = await readFile(path, 'utf8')
  return { canceled: false, path, content }
})

ipcMain.handle('myreader:open-folder-dialog', async (): Promise<OpenFolderResult> => {
  const win = BrowserWindow.getFocusedWindow()
  const opts = { properties: ['openDirectory' as const] }
  const { canceled, filePaths } = win
    ? await dialog.showOpenDialog(win, opts)
    : await dialog.showOpenDialog(opts)
  if (canceled || !filePaths?.[0]) return { canceled: true }
  return { canceled: false, path: filePaths[0] }
})

ipcMain.handle('myreader:open-image-dialog', async (event): Promise<OpenImageResult> => {
  const win =
    BrowserWindow.fromWebContents(event.sender) ?? BrowserWindow.getFocusedWindow()
  const opts = {
    properties: ['openFile' as const],
    filters: [
      {
        name: '图片',
        extensions: ['png', 'jpg', 'jpeg', 'gif', 'webp', 'svg', 'bmp', 'ico', 'avif']
      }
    ]
  }
  if (win) {
    win.focus()
    win.show()
  }
  const { canceled, filePaths } = win
    ? await dialog.showOpenDialog(win, opts)
    : await dialog.showOpenDialog(opts)
  if (canceled || !filePaths?.[0]) return { canceled: true }
  const path = filePaths[0]
  return { canceled: false, path, url: pathToFileURL(path).href }
})

ipcMain.handle(
  'myreader:save-dialog',
  async (_evt, defaultPath?: string): Promise<SaveDialogResult> => {
    const win = BrowserWindow.getFocusedWindow()
    const { canceled, filePath } = win
      ? await dialog.showSaveDialog(win, {
          defaultPath,
          filters: [{ name: 'Markdown', extensions: ['md'] }]
        })
      : await dialog.showSaveDialog({
          defaultPath,
          filters: [{ name: 'Markdown', extensions: ['md'] }]
        })
    if (canceled || !filePath) return { canceled: true }
    return { canceled: false, path: filePath }
  }
)

ipcMain.handle('myreader:read-file', async (_evt, filePath: string): Promise<string> => {
  return readFile(filePath, 'utf8')
})

ipcMain.handle(
  'myreader:write-file',
  async (_evt, filePath: string, content: string): Promise<void> => {
    await writeFile(filePath, content, 'utf8')
  }
)

ipcMain.handle('myreader:list-directory', async (_evt, dirPath: string): Promise<ListDirResult> => {
  return listDirectoryImpl(dirPath)
})

ipcMain.handle('myreader:parent-directory', (_evt, dirPath: string): string => {
  return dirname(dirPath)
})

ipcMain.handle('myreader:default-directory', async (): Promise<string> => {
  return app.getPath('documents')
})

ipcMain.handle('myreader:delete-file', async (_evt, filePath: string): Promise<void> => {
  if (typeof filePath !== 'string' || filePath.length === 0) {
    throw new Error('Invalid path')
  }
  await unlink(filePath)
})

ipcMain.handle(
  'myreader:rename-path',
  async (_evt, oldPath: string, newName: string): Promise<{ newPath: string }> => {
    if (typeof oldPath !== 'string' || typeof newName !== 'string') {
      throw new Error('Invalid arguments')
    }
    const clean = newName.replace(/[/\\]/g, '').trim()
    if (!clean) {
      throw new Error('Empty name')
    }
    const parent = dirname(oldPath)
    const newPath = join(parent, clean)
    if (normalize(newPath) === normalize(oldPath)) {
      return { newPath: oldPath }
    }
    await rename(oldPath, newPath)
    return { newPath }
  }
)

ipcMain.on('myreader:allow-close', (event) => {
  const win = BrowserWindow.fromWebContents(event.sender)
  if (!win) return
  ;(win as BrowserWindow & { __myreaderForceClose?: boolean }).__myreaderForceClose = true
  win.close()
})

app.whenReady().then(() => {
  Menu.setApplicationMenu(buildMenu())
  createWindow()
  app.on('activate', () => {
    if (BrowserWindow.getAllWindows().length === 0) {
      createWindow()
    }
  })
})

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit()
  }
})