import { atom, computed } from 'nanostores'

import { defaultBindings, KEYBIND_ACTION_IDS, keybindAction, type KeybindBindings } from '@/lib/keybinds/actions'
import { canonicalizeCombo } from '@/lib/keybinds/combo'
import { arraysEqual, persistString, storedString } from '@/lib/storage'

const STORAGE_KEY = 'hermes.desktop.keybinds'

// Defaults overlaid with the user's stored overrides. Unknown / stale action ids
// are dropped; actions added in a later release pick up their shipped default.
function loadBindings(): KeybindBindings {
  const base = defaultBindings()
  const raw = storedString(STORAGE_KEY)

  if (!raw) {
    return base
  }

  try {
    const parsed = JSON.parse(raw) as Record<string, unknown>

    for (const id of KEYBIND_ACTION_IDS) {
      const value = parsed[id]

      if (Array.isArray(value)) {
        base[id] = value.filter((combo): combo is string => typeof combo === 'string')
      }
    }
  } catch {
    // Corrupt storage falls back to defaults.
  }

  return base
}

// Persist only the actions whose combos differ from their shipped default, so
// changing a default never gets shadowed by a stored snapshot.
function persistBindings(bindings: KeybindBindings): void {
  const defaults = defaultBindings()
  const diff: KeybindBindings = {}

  for (const id of KEYBIND_ACTION_IDS) {
    const current = bindings[id] ?? []

    if (!arraysEqual(current, defaults[id] ?? [])) {
      diff[id] = current
    }
  }

  persistString(STORAGE_KEY, JSON.stringify(diff))
}

export const $bindings = atom<KeybindBindings>(loadBindings())

$bindings.subscribe(persistBindings)

// Reverse lookup combo → actionId for dispatch. First action wins on conflict;
// the panel/edit overlay surface conflicts so users can resolve them. Keys go
// through `canonicalizeCombo` so a `ctrl+…` binding resolves everywhere.
export const $comboIndex = computed($bindings, bindings => {
  const index = new Map<string, string>()

  for (const id of KEYBIND_ACTION_IDS) {
    for (const combo of bindings[id] ?? []) {
      const key = canonicalizeCombo(combo)

      if (!index.has(key)) {
        index.set(key, id)
      }
    }
  }

  return index
})

export function setBinding(actionId: string, combos: string[]): void {
  if (!keybindAction(actionId)) {
    return
  }

  $bindings.set({ ...$bindings.get(), [actionId]: [...combos] })
}

export function resetBinding(actionId: string): void {
  const action = keybindAction(actionId)

  if (!action) {
    return
  }

  $bindings.set({ ...$bindings.get(), [actionId]: [...action.defaults] })
}

export function resetAllBindings(): void {
  $bindings.set(defaultBindings())
}

// Other actions that already use `combo` (excluding `actionId` itself).
export function conflictsFor(actionId: string, combo: string): string[] {
  const bindings = $bindings.get()

  return KEYBIND_ACTION_IDS.filter(id => id !== actionId && (bindings[id] ?? []).includes(combo))
}

// ── Capture ─────────────────────────────────────────────────────────────────
// `$capture` is the action currently listening for its next keypress (a panel
// row armed for rebinding). Session-only — never persisted.

export const $capture = atom<string | null>(null)

export function beginCapture(actionId: string): void {
  $capture.set(actionId)
}

export function endCapture(): void {
  $capture.set(null)
}

// ── Panel ───────────────────────────────────────────────────────────────────

export const $keybindPanelOpen = atom(false)

export function openKeybindPanel(): void {
  $keybindPanelOpen.set(true)
}

export function closeKeybindPanel(): void {
  $keybindPanelOpen.set(false)
  $capture.set(null)
}

export function toggleKeybindPanel(): void {
  if ($keybindPanelOpen.get()) {
    closeKeybindPanel()
  } else {
    openKeybindPanel()
  }
}