import { ELECTRON_IPC_CHANNELS, type ElectronIpcChannel } from './channels'

type Validator = (payload: unknown) => boolean

const isRecord = (value: unknown): value is Record<string, unknown> =>
  typeof value === 'object' && value !== null && !Array.isArray(value)

const noPayload: Validator = value => value === undefined
const optionalRecord: Validator = value => value === undefined || isRecord(value)
const stringPayload: Validator = value => typeof value === 'string'
const booleanPayload: Validator = value => typeof value === 'boolean'
const hasOnlyKeys = (value: Record<string, unknown>, allowedKeys: string[]) =>
  Object.keys(value).every(key => allowedKeys.includes(key))

const MAX_TERMINAL_DIMENSION = 1_000
const MAX_TERMINAL_CWD_LENGTH = 4_096
const MAX_TERMINAL_WRITE_LENGTH = 1_048_576

const isTerminalSessionId = (value: unknown) =>
  typeof value === 'number'
  && Number.isSafeInteger(value)
  && value > 0

const isTerminalDimension = (value: unknown) =>
  typeof value === 'number'
  && Number.isInteger(value)
  && value > 0
  && value <= MAX_TERMINAL_DIMENSION

const sessionIdPayload: Validator = value =>
  typeof value === 'string'
  && value.length > 0
  && value.length <= 200
  && /^[A-Za-z0-9._:-]+$/.test(value)

const isSafeUiLabel = (value: unknown) =>
  typeof value === 'string'
  && value.trim().length > 0
  && value.length <= 120
  && !/[\u0000-\u001f\u007f-\u009f]/.test(value)

const hasValidPetIdentity = (value: Record<string, unknown>): boolean => {
  if (
    typeof value.slug !== 'string'
    || value.slug.length === 0
    || value.slug.length > 73
    || !/^[a-z0-9]+(?:-[a-z0-9]+)*$/.test(value.slug)
  ) return false
  return typeof value.displayName === 'string'
    && value.displayName.trim().length > 0
    && value.displayName.length <= 80
    && typeof value.description === 'string'
    && value.description.trim().length > 0
    && value.description.length <= 500
}

const petCreateFromAtlas: Validator = value => {
  if (!isRecord(value) || !hasOnlyKeys(value, [
    'slug',
    'displayName',
    'description',
    'dialogTitle',
    'dialogFilterName',
  ])) return false
  return hasValidPetIdentity(value)
    && (value.dialogTitle === undefined || isSafeUiLabel(value.dialogTitle))
    && (value.dialogFilterName === undefined || isSafeUiLabel(value.dialogFilterName))
}

const petPickSourceSheet: Validator = value => {
  if (value === undefined) return true
  if (!isRecord(value) || !hasOnlyKeys(value, ['dialogTitle', 'dialogFilterName'])) return false
  return (value.dialogTitle === undefined || isSafeUiLabel(value.dialogTitle))
    && (value.dialogFilterName === undefined || isSafeUiLabel(value.dialogFilterName))
}

/** Matches DEFAULT_CUSTOM_PET_MAX_IMAGE_BYTES so oversized atlases are dropped at the boundary. */
const MAX_PET_ATLAS_PAYLOAD_BYTES = 8 * 1024 * 1024

const petCreateFromAtlasBytes: Validator = value => {
  if (!isRecord(value) || !hasOnlyKeys(value, [
    'slug',
    'displayName',
    'description',
    'atlasData',
    'mimeType',
  ])) return false
  if (
    !(value.atlasData instanceof Uint8Array)
    || value.atlasData.byteLength === 0
    || value.atlasData.byteLength > MAX_PET_ATLAS_PAYLOAD_BYTES
  ) return false
  if (value.mimeType !== 'image/png' && value.mimeType !== 'image/webp') return false
  return hasValidPetIdentity(value)
}

const petContextMenu: Validator = value => {
  if (!isRecord(value) || !hasOnlyKeys(value, ['closeLabel'])) return false
  if (typeof value.closeLabel !== 'string' || value.closeLabel.length > 80) return false
  const closeLabel = value.closeLabel.trim()
  return closeLabel.length > 0
    && closeLabel.length <= 80
    && !/[\u0000-\u001f\u007f-\u009f]/.test(value.closeLabel)
}

const petWindowDrag: Validator = value => {
  if (!isRecord(value) || !hasOnlyKeys(value, ['phase', 'x', 'y'])) return false
  if (value.phase !== 'start' && value.phase !== 'move' && value.phase !== 'end') return false
  return ['x', 'y'].every((key) =>
    typeof value[key] === 'number'
    && Number.isFinite(value[key])
    && Math.abs(value[key]) <= 1_000_000)
}

const commandInvoke: Validator = value =>
  isRecord(value)
  && typeof value.command === 'string'
  && value.command.length > 0
  && (value.args === undefined || isRecord(value.args))

const terminalWrite: Validator = value =>
  isRecord(value)
  && hasOnlyKeys(value, ['sessionId', 'data'])
  && isTerminalSessionId(value.sessionId)
  && typeof value.data === 'string'
  && value.data.length <= MAX_TERMINAL_WRITE_LENGTH

const terminalSpawn: Validator = value =>
  value === undefined
  || (
    isRecord(value)
    && hasOnlyKeys(value, ['cols', 'rows', 'cwd'])
    && (value.cols === undefined || isTerminalDimension(value.cols))
    && (value.rows === undefined || isTerminalDimension(value.rows))
    && (
      value.cwd === undefined
      || (
        typeof value.cwd === 'string'
        && value.cwd.length <= MAX_TERMINAL_CWD_LENGTH
        && !value.cwd.includes('\0')
      )
    )
  )

const terminalResize: Validator = value =>
  isRecord(value)
  && hasOnlyKeys(value, ['sessionId', 'cols', 'rows'])
  && isTerminalSessionId(value.sessionId)
  && isTerminalDimension(value.cols)
  && isTerminalDimension(value.rows)

const terminalSessionId: Validator = value =>
  isRecord(value)
  && hasOnlyKeys(value, ['sessionId'])
  && isTerminalSessionId(value.sessionId)

const boundsPayload: Validator = value =>
  isRecord(value)
  && typeof value.x === 'number'
  && typeof value.y === 'number'
  && typeof value.width === 'number'
  && typeof value.height === 'number'

const petInteractiveRegions: Validator = value =>
  Array.isArray(value)
  && value.length > 0
  && value.length <= 8
  && value.every((region) =>
    isRecord(region)
    && hasOnlyKeys(region, ['x', 'y', 'width', 'height'])
    && ['x', 'y', 'width', 'height'].every((key) =>
      typeof region[key] === 'number'
      && Number.isInteger(region[key])
      && region[key] >= (key === 'width' || key === 'height' ? 1 : 0)
      && region[key] <= 2_000))

const urlWithOptionalBounds: Validator = value =>
  isRecord(value)
  && typeof value.url === 'string'
  && (value.bounds === undefined || boundsPayload(value.bounds))

const zoomPayload: Validator = value => typeof value === 'number' && Number.isFinite(value)

// The colors reach BrowserWindow.setBackgroundColor, so they are pinned to a
// literal 6-digit #RRGGBB. This is load-bearing, not tidiness: that API also
// accepts #AARRGGBB, so an 8-digit value would let a compromised renderer make
// a window translucent or fully transparent — click-through and overlay
// spoofing. Do not relax this into "any CSS color".
const HEX_COLOR = /^#[0-9a-fA-F]{6}$/
const appliedAppearance: Validator = value =>
  isRecord(value)
  && hasOnlyKeys(value, ['isDark', 'background', 'lightBackground', 'followSystem'])
  && typeof value.isDark === 'boolean'
  && typeof value.followSystem === 'boolean'
  && typeof value.background === 'string'
  && HEX_COLOR.test(value.background)
  && typeof value.lightBackground === 'string'
  && HEX_COLOR.test(value.lightBackground)

const updateCheckOptions: Validator = value => {
  if (value === undefined) return true
  if (!isRecord(value) || !hasOnlyKeys(value, ['proxy'])) return false
  return value.proxy === undefined || (typeof value.proxy === 'string' && value.proxy.trim().length > 0)
}

export const ELECTRON_IPC_VALIDATORS = {
  [ELECTRON_IPC_CHANNELS.appGetVersion]: noPayload,
  [ELECTRON_IPC_CHANNELS.runtimeGetServerUrl]: noPayload,
  [ELECTRON_IPC_CHANNELS.runtimeGetLocalAccessToken]: noPayload,
  [ELECTRON_IPC_CHANNELS.runtimeGetPetAccessToken]: noPayload,
  [ELECTRON_IPC_CHANNELS.commandInvoke]: commandInvoke,
  [ELECTRON_IPC_CHANNELS.clipboardReadText]: noPayload,
  [ELECTRON_IPC_CHANNELS.clipboardWriteText]: stringPayload,
  [ELECTRON_IPC_CHANNELS.shellOpen]: stringPayload,
  [ELECTRON_IPC_CHANNELS.shellOpenPath]: stringPayload,
  [ELECTRON_IPC_CHANNELS.traceOpenWindow]: sessionIdPayload,
  [ELECTRON_IPC_CHANNELS.petsList]: noPayload,
  [ELECTRON_IPC_CHANNELS.petsCreateFromImage]: petCreateFromAtlas,
  [ELECTRON_IPC_CHANNELS.petsCreateFromAtlas]: petCreateFromAtlas,
  [ELECTRON_IPC_CHANNELS.petsPickSourceSheet]: petPickSourceSheet,
  [ELECTRON_IPC_CHANNELS.petsCreateFromAtlasBytes]: petCreateFromAtlasBytes,
  [ELECTRON_IPC_CHANNELS.petsOpenFolder]: noPayload,
  [ELECTRON_IPC_CHANNELS.petsShow]: noPayload,
  [ELECTRON_IPC_CHANNELS.petsHide]: noPayload,
  [ELECTRON_IPC_CHANNELS.petsShowContextMenu]: petContextMenu,
  [ELECTRON_IPC_CHANNELS.petsDragWindow]: petWindowDrag,
  [ELECTRON_IPC_CHANNELS.petsSetIgnoreMouseEvents]: booleanPayload,
  [ELECTRON_IPC_CHANNELS.petsSetInteractiveRegions]: petInteractiveRegions,
  [ELECTRON_IPC_CHANNELS.petsFocusMainWindow]: noPayload,
  [ELECTRON_IPC_CHANNELS.petsFocusSession]: sessionIdPayload,
  [ELECTRON_IPC_CHANNELS.dialogOpen]: optionalRecord,
  [ELECTRON_IPC_CHANNELS.dialogSave]: optionalRecord,
  [ELECTRON_IPC_CHANNELS.updateCheck]: updateCheckOptions,
  [ELECTRON_IPC_CHANNELS.updateDownload]: noPayload,
  [ELECTRON_IPC_CHANNELS.updateInstall]: noPayload,
  [ELECTRON_IPC_CHANNELS.updatePrepareInstall]: noPayload,
  [ELECTRON_IPC_CHANNELS.updateCancelInstall]: noPayload,
  [ELECTRON_IPC_CHANNELS.updateRelaunch]: noPayload,
  [ELECTRON_IPC_CHANNELS.notificationPermissionState]: noPayload,
  [ELECTRON_IPC_CHANNELS.notificationRequestPermission]: noPayload,
  [ELECTRON_IPC_CHANNELS.notificationSend]: optionalRecord,
  [ELECTRON_IPC_CHANNELS.notificationActionAck]: optionalRecord,
  [ELECTRON_IPC_CHANNELS.windowMinimize]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowToggleMaximize]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowClose]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowStartDragging]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowRequestAttention]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowFocus]: noPayload,
  [ELECTRON_IPC_CHANNELS.windowIsMaximized]: noPayload,
  [ELECTRON_IPC_CHANNELS.terminalSpawn]: terminalSpawn,
  [ELECTRON_IPC_CHANNELS.terminalWrite]: terminalWrite,
  [ELECTRON_IPC_CHANNELS.terminalResize]: terminalResize,
  [ELECTRON_IPC_CHANNELS.terminalKill]: terminalSessionId,
  [ELECTRON_IPC_CHANNELS.terminalGetBashPath]: noPayload,
  [ELECTRON_IPC_CHANNELS.terminalSetBashPath]: value => value === null || stringPayload(value),
  [ELECTRON_IPC_CHANNELS.previewOpen]: urlWithOptionalBounds,
  [ELECTRON_IPC_CHANNELS.previewNavigate]: stringPayload,
  [ELECTRON_IPC_CHANNELS.previewSetBounds]: boundsPayload,
  [ELECTRON_IPC_CHANNELS.previewSetVisible]: booleanPayload,
  [ELECTRON_IPC_CHANNELS.previewSetZoom]: zoomPayload,
  [ELECTRON_IPC_CHANNELS.previewClose]: noPayload,
  [ELECTRON_IPC_CHANNELS.previewMessage]: () => true,
  [ELECTRON_IPC_CHANNELS.appModeGet]: noPayload,
  [ELECTRON_IPC_CHANNELS.appModeSet]: optionalRecord,
  [ELECTRON_IPC_CHANNELS.appModePrepareRestart]: noPayload,
  [ELECTRON_IPC_CHANNELS.appModeRestart]: noPayload,
  [ELECTRON_IPC_CHANNELS.adaptersRestartSidecar]: noPayload,
  [ELECTRON_IPC_CHANNELS.zoomSet]: zoomPayload,
  [ELECTRON_IPC_CHANNELS.appearanceSetApplied]: appliedAppearance,
} satisfies Record<ElectronIpcChannel, Validator>

const allowedChannels = new Set<ElectronIpcChannel>(
  Object.values(ELECTRON_IPC_CHANNELS),
)

const petWindowChannels = new Set<ElectronIpcChannel>([
  ELECTRON_IPC_CHANNELS.runtimeGetServerUrl,
  ELECTRON_IPC_CHANNELS.runtimeGetPetAccessToken,
  ELECTRON_IPC_CHANNELS.petsList,
  ELECTRON_IPC_CHANNELS.petsHide,
  ELECTRON_IPC_CHANNELS.petsShowContextMenu,
  ELECTRON_IPC_CHANNELS.petsDragWindow,
  ELECTRON_IPC_CHANNELS.petsSetIgnoreMouseEvents,
  ELECTRON_IPC_CHANNELS.petsSetInteractiveRegions,
  ELECTRON_IPC_CHANNELS.petsFocusMainWindow,
  ELECTRON_IPC_CHANNELS.petsFocusSession,
])

export function isElectronIpcChannel(channel: string): channel is ElectronIpcChannel {
  return allowedChannels.has(channel as ElectronIpcChannel)
}

export function validateElectronIpcPayload(channel: ElectronIpcChannel, payload: unknown): boolean {
  return ELECTRON_IPC_VALIDATORS[channel](payload)
}

export function isElectronIpcChannelAllowedForPetWindow(channel: ElectronIpcChannel): boolean {
  return petWindowChannels.has(channel)
}