import { create } from 'zustand';
import type { AudioOutputRoute, EQBand, EQMode, EQPreset } from '@/types/audio';
import { AstraLibraryData } from '../../modules/astra-library-scanner';
import { getNativeSettings, setNativeSetting } from '@/db/nativeSettings';
import {
  EQ_MAX_BANDS,
  clampEQFrequency,
  clampEQGain,
  clampEQQ,
  clampPreamp,
  createNormalizedEQBand,
  dbToLinear,
  flattenBandsForNative,
} from '@/audio/eq';
import { createBuiltInPresets, createDefaultBands, FLAT_PRESET_ID, genEqId } from '@/audio/eqPresets';
import {
  buildGraphicBands,
  createFlatGraphicGains,
  deriveGraphicGains,
  parseGraphicGains,
} from '@/audio/graphicEq';
import {
  normalizeAudioOutputRoute,
  parseEQRouteProfilesJson,
} from '@/audio/eqRouteProfiles';
import {
  migrateLegacyEQRouteProfiles,
  observeEQOutputDevice,
  parseEQDevicePresetStateJson,
  presetForOutputRouteTransition,
  pruneEQDevicePresetAssignments,
  removePresetDeviceAssignments,
  replacePresetDeviceAssignments,
  stringifyEQDevicePresetState,
  type EQDevicePresetState,
  type KnownEQOutputDevice,
} from '@/audio/eqDevicePresets';
import { setEqBandsNative, setEqEnabledNative, setEqPreampNative } from '@/audio/eqNative';

/**
 * Parametric EQ state — SQLite (settings table) is the source of truth, mirrored
 * in memory (mirrors the settingsStore pattern; no zustand-persist). Every band/
 * preamp/enable change pushes params to the native EqAudioProcessor via _syncToNative
 * (immediate, for live audio) and debounce-persists to SQLite.
 */
const ENABLED_KEY = 'eq_enabled';
const PREAMP_KEY = 'eq_preamp';
const BANDS_KEY = 'eq_bands';
const ACTIVE_PRESET_KEY = 'eq_active_preset';
const CUSTOM_PRESETS_KEY = 'eq_custom_presets';
const MODE_KEY = 'eq_mode';
const GRAPHIC_GAINS_KEY = 'eq_graphic_gains';
const ROUTE_PROFILES_KEY = 'eq_route_profiles_v1';
const DEVICE_PRESETS_KEY = 'eq_device_preset_assignments_v1';

const PERSIST_DEBOUNCE_MS = 250;

function safeJsonParse(json: string | null): unknown {
  if (!json) return null;
  try {
    return JSON.parse(json);
  } catch {
    return null;
  }
}

function parseBands(json: string | null): EQBand[] | null {
  if (!json) return null;
  try {
    const arr = JSON.parse(json);
    if (!Array.isArray(arr) || arr.length === 0) return null;
    return arr.slice(0, EQ_MAX_BANDS).map((raw) => createNormalizedEQBand(raw, genEqId()));
  } catch {
    return null;
  }
}

function parseCustomPresets(json: string | null): EQPreset[] {
  if (!json) return [];
  try {
    const arr = JSON.parse(json);
    if (!Array.isArray(arr)) return [];
    return arr
      .filter(
        (p): p is { id?: string; name: string; preamp?: number; bands?: unknown[]; mode?: unknown; graphicGains?: unknown } =>
          !!p && typeof p.name === 'string'
      )
      .map((p) => {
        // Invalid/missing graphic gains degrade the preset to parametric — the
        // compiled bands snapshot below sounds identical.
        const graphicGains = p.mode === 'graphic' ? parseGraphicGains(p.graphicGains) : null;
        return {
          // Keep the stored id so a persisted activePresetId still matches on reload.
          id: typeof p.id === 'string' && p.id.length > 0 ? p.id : genEqId(),
          name: p.name,
          preamp: clampPreamp(typeof p.preamp === 'number' ? p.preamp : 0),
          bands: Array.isArray(p.bands)
            ? p.bands.slice(0, EQ_MAX_BANDS).map((b) => createNormalizedEQBand(b as object, genEqId()))
            : createDefaultBands(),
          isCustom: true,
          ...(graphicGains ? { mode: 'graphic' as const, graphicGains } : {}),
        };
      });
  } catch {
    return [];
  }
}

interface EQStore {
  enabled: boolean;
  preamp: number; // dB
  bands: EQBand[];
  mode: EQMode; // which editor drives the native bands (preamp/enabled are shared)
  graphicGains: number[]; // graphic-mode slider gains (dB), independent of `bands`
  presets: EQPreset[]; // built-in + custom
  activePresetId: string | null; // null = manually edited ("Custom")
  activeBandId: string | null; // UI selection shared by curve / strip / panel
  activeOutputRoute: AudioOutputRoute | null;
  knownOutputDevices: Record<string, KnownEQOutputDevice>;
  devicePresetAssignments: Record<string, string>;
  loaded: boolean;

  load: () => Promise<void>;
  setEnabled: (enabled: boolean) => void;
  toggleEnabled: () => void;
  setPreamp: (db: number) => void;
  setMode: (mode: EQMode) => void;
  setGraphicGain: (index: number, gainDb: number) => void;
  addBand: (band?: Partial<EQBand>) => void;
  removeBand: (id: string) => void;
  updateBand: (id: string, updates: Partial<EQBand>) => void;
  selectBand: (id: string | null) => void;
  applyPreset: (presetId: string) => void;
  resetToFlat: () => void;
  saveCustomPreset: (name: string) => string;
  deleteCustomPreset: (presetId: string) => void;
  importPreset: (preset: EQPreset) => void;
  assignPresetToDevices: (presetId: string, deviceKeys: readonly string[]) => void;
  setOutputRoute: (route: AudioOutputRoute | null) => Promise<void>;

  _syncToNative: () => void;
}

let persistTimer: ReturnType<typeof setTimeout> | null = null;

export const useEQStore = create<EQStore>((set, get) => {
  function syncToNative(): void {
    const { enabled, preamp, bands, mode, graphicGains } = get();
    const activeBands = mode === 'graphic' ? buildGraphicBands(graphicGains) : bands;
    setEqEnabledNative(enabled);
    setEqPreampNative(enabled ? dbToLinear(preamp) : 1);
    setEqBandsNative(flattenBandsForNative(activeBands));
  }

  function currentDevicePresetState(): EQDevicePresetState {
    const { knownOutputDevices, devicePresetAssignments } = get();
    return {
      version: 1,
      devices: knownOutputDevices,
      assignments: devicePresetAssignments,
    };
  }

  function schedulePersist(): void {
    if (persistTimer) clearTimeout(persistTimer);
    persistTimer = setTimeout(() => {
      persistTimer = null;
      void persistNow();
    }, PERSIST_DEBOUNCE_MS);
  }

  async function persistNow(): Promise<void> {
    const {
      enabled,
      preamp,
      bands,
      mode,
      graphicGains,
      activePresetId,
      presets,
      knownOutputDevices,
      devicePresetAssignments,
    } = get();
    const custom = presets.filter((p) => p.isCustom);
    const devicePresetState: EQDevicePresetState = {
      version: 1,
      devices: knownOutputDevices,
      assignments: devicePresetAssignments,
    };
    try {
      await AstraLibraryData.setSettings({
        [ENABLED_KEY]: enabled ? 'true' : 'false',
        [PREAMP_KEY]: String(preamp),
        [BANDS_KEY]: JSON.stringify(bands),
        [MODE_KEY]: mode,
        [GRAPHIC_GAINS_KEY]: JSON.stringify(graphicGains),
        [ACTIVE_PRESET_KEY]: activePresetId ?? '',
        [DEVICE_PRESETS_KEY]: stringifyEQDevicePresetState(devicePresetState),
        [CUSTOM_PRESETS_KEY]: JSON.stringify(
            custom.map((p) => ({
              id: p.id,
              name: p.name,
              preamp: p.preamp,
              bands: p.bands,
              ...(p.mode === 'graphic' ? { mode: p.mode, graphicGains: p.graphicGains } : {}),
            }))
          ),
      });
    } catch {
      /* persistence failure is non-fatal */
    }
  }

  /** Mark the current band set as a manual edit (no longer matches a preset). */
  function markEdited(patch: Partial<EQStore>): void {
    set({ ...patch, activePresetId: null });
    syncToNative();
    schedulePersist();
  }

  return {
    enabled: false,
    preamp: 0,
    bands: createDefaultBands(),
    mode: 'parametric',
    graphicGains: createFlatGraphicGains(),
    presets: createBuiltInPresets(),
    activePresetId: FLAT_PRESET_ID,
    activeBandId: null,
    activeOutputRoute: null,
    knownOutputDevices: {},
    devicePresetAssignments: {},
    loaded: false,

    load: async () => {
      if (get().loaded) return;
      const values = await getNativeSettings([
        ENABLED_KEY,
        PREAMP_KEY,
        BANDS_KEY,
        MODE_KEY,
        GRAPHIC_GAINS_KEY,
        ACTIVE_PRESET_KEY,
        CUSTOM_PRESETS_KEY,
        DEVICE_PRESETS_KEY,
        ROUTE_PROFILES_KEY,
      ]);
      const enabledRaw = values[ENABLED_KEY];
      const preampRaw = values[PREAMP_KEY];
      const bandsRaw = values[BANDS_KEY];
      const modeRaw = values[MODE_KEY];
      const gainsRaw = values[GRAPHIC_GAINS_KEY];
      const activeRaw = values[ACTIVE_PRESET_KEY];
      const customRaw = values[CUSTOM_PRESETS_KEY];
      const devicePresetsRaw = values[DEVICE_PRESETS_KEY];
      const routeProfilesRaw = values[ROUTE_PROFILES_KEY];

      const bands = parseBands(bandsRaw) ?? createDefaultBands();
      const presets = [...createBuiltInPresets(), ...parseCustomPresets(customRaw)];
      const storedActive = activeRaw && activeRaw.length > 0 ? activeRaw : null;
      const parsedDeviceState = devicePresetsRaw === null
        ? migrateLegacyEQRouteProfiles(parseEQRouteProfilesJson(routeProfilesRaw, genEqId))
        : parseEQDevicePresetStateJson(devicePresetsRaw);
      const deviceState = pruneEQDevicePresetAssignments(
        parsedDeviceState,
        (presetId) => presets.some((preset) => preset.id === presetId)
      );

      set({
        enabled: enabledRaw === 'true',
        preamp: clampPreamp(Number(preampRaw) || 0),
        bands,
        // Missing key (pre-graphic installs) → parametric.
        mode: modeRaw === 'graphic' ? 'graphic' : 'parametric',
        graphicGains: parseGraphicGains(safeJsonParse(gainsRaw)) ?? createFlatGraphicGains(),
        presets,
        // Missing/deleted preset references fall back to the freely editable state.
        activePresetId: presets.some((p) => p.id === storedActive) ? storedActive : null,
        activeBandId: bands[0]?.id ?? null,
        knownOutputDevices: deviceState.devices,
        devicePresetAssignments: deviceState.assignments,
        loaded: true,
      });
      syncToNative();

      // The presence of the new envelope is the migration marker. The legacy
      // snapshots remain unread after this write and can no longer affect EQ.
      if (devicePresetsRaw === null) {
        try {
          await setNativeSetting(DEVICE_PRESETS_KEY, stringifyEQDevicePresetState(deviceState));
        } catch {
          /* migration persistence failure is non-fatal and safe to retry */
        }
      }
    },

    setEnabled: (enabled) => {
      set({ enabled });
      syncToNative();
      schedulePersist();
    },

    toggleEnabled: () => {
      set({ enabled: !get().enabled });
      syncToNative();
      schedulePersist();
    },

    setPreamp: (db) => markEdited({ preamp: clampPreamp(db) }),

    setMode: (mode) => {
      if (get().mode === mode) return;
      // Non-destructive: both modes keep their own band state; only the preset
      // label stops describing what's audible.
      set({ mode, activePresetId: null });
      syncToNative();
      schedulePersist();
    },

    setGraphicGain: (index, gainDb) => {
      const gains = get().graphicGains;
      if (index < 0 || index >= gains.length) return;
      const next = gains.slice();
      next[index] = clampEQGain(gainDb);
      markEdited({ graphicGains: next });
    },

    addBand: (partial) => {
      const { bands } = get();
      if (bands.length >= EQ_MAX_BANDS) return;
      const band = createNormalizedEQBand(
        {
          type: partial?.type ?? 'peaking',
          frequency: partial?.frequency ?? 1000,
          gain: partial?.gain ?? 0,
          Q: partial?.Q ?? 1.0,
          enabled: partial?.enabled ?? true,
        },
        genEqId()
      );
      const next = [...bands, band].sort((a, b) => a.frequency - b.frequency);
      markEdited({ bands: next, activeBandId: band.id });
    },

    removeBand: (id) => {
      const { bands, activeBandId } = get();
      if (bands.length <= 1) return;
      const next = bands.filter((b) => b.id !== id);
      markEdited({
        bands: next,
        activeBandId: activeBandId === id ? (next[0]?.id ?? null) : activeBandId,
      });
    },

    updateBand: (id, updates) => {
      const next = get().bands.map((b) => {
        if (b.id !== id) return b;
        const merged: EQBand = { ...b, ...updates };
        if (updates.frequency !== undefined) merged.frequency = clampEQFrequency(updates.frequency);
        if (updates.gain !== undefined) merged.gain = clampEQGain(updates.gain);
        if (updates.Q !== undefined) merged.Q = clampEQQ(updates.Q);
        return merged;
      });
      markEdited({
        bands: updates.frequency !== undefined ? next.sort((a, b) => a.frequency - b.frequency) : next,
      });
    },

    selectBand: (id) => set({ activeBandId: id }),

    applyPreset: (presetId) => {
      const preset = get().presets.find((p) => p.id === presetId);
      if (!preset) return;
      // Custom presets re-open in the mode they were saved in (each branch leaves
      // the other mode's band state untouched); built-ins are mode-agnostic and
      // apply in whichever mode is active.
      const graphicGains = preset.mode === 'graphic' ? parseGraphicGains(preset.graphicGains) : null;
      if (graphicGains) {
        set({
          mode: 'graphic',
          graphicGains,
          preamp: clampPreamp(preset.preamp),
          activePresetId: presetId,
        });
      } else if (!preset.isCustom && get().mode === 'graphic') {
        // Project the parametric built-in onto the 5 sliders (its response
        // sampled at each band frequency) instead of yanking the user out of
        // graphic mode.
        set({
          graphicGains: deriveGraphicGains(preset.bands),
          preamp: clampPreamp(preset.preamp),
          activePresetId: presetId,
        });
      } else {
        const bands = preset.bands.map((b) => createNormalizedEQBand(b, genEqId()));
        set({
          mode: 'parametric',
          bands,
          preamp: clampPreamp(preset.preamp),
          activePresetId: presetId,
          activeBandId: bands[0]?.id ?? null,
        });
      }
      syncToNative();
      schedulePersist();
    },

    resetToFlat: () => {
      // In graphic mode, flatten in place — applying the parametric Flat preset
      // would silently switch modes.
      if (get().mode === 'graphic') {
        set({ graphicGains: createFlatGraphicGains(), preamp: 0, activePresetId: null });
        syncToNative();
        schedulePersist();
        return;
      }
      get().applyPreset(FLAT_PRESET_ID);
    },

    saveCustomPreset: (name) => {
      const { bands, mode, graphicGains, preamp, presets } = get();
      const preset: EQPreset =
        mode === 'graphic'
          ? {
              id: genEqId(),
              name: name.trim() || 'Custom Preset',
              preamp,
              // Compiled snapshot so builds without graphic support (or corrupt
              // gains) still load an identical parametric preset.
              bands: buildGraphicBands(graphicGains).map((b) => ({ ...b, id: genEqId() })),
              mode: 'graphic',
              graphicGains: [...graphicGains],
              isCustom: true,
            }
          : {
              id: genEqId(),
              name: name.trim() || 'Custom Preset',
              preamp,
              bands: bands.map((b) => ({ ...b, id: genEqId() })),
              isCustom: true,
            };
      set({ presets: [...presets, preset], activePresetId: preset.id });
      schedulePersist();
      return preset.id;
    },

    deleteCustomPreset: (presetId) => {
      const { presets, activePresetId } = get();
      const deviceState = removePresetDeviceAssignments(currentDevicePresetState(), presetId);
      set({
        presets: presets.filter((p) => p.id !== presetId),
        activePresetId: activePresetId === presetId ? null : activePresetId,
        devicePresetAssignments: deviceState.assignments,
      });
      schedulePersist();
    },

    importPreset: (preset) => {
      const graphicGains = preset.mode === 'graphic' ? parseGraphicGains(preset.graphicGains) : null;
      const stored: EQPreset = {
        id: genEqId(),
        name: preset.name,
        preamp: clampPreamp(preset.preamp),
        bands: preset.bands.slice(0, EQ_MAX_BANDS).map((band) => createNormalizedEQBand(band, genEqId())),
        isCustom: true,
        ...(graphicGains ? { mode: 'graphic' as const, graphicGains } : {}),
      };
      set({ presets: [...get().presets, stored] });
      get().applyPreset(stored.id);
    },

    assignPresetToDevices: (presetId, deviceKeys) => {
      if (!get().presets.some((preset) => preset.id === presetId)) return;
      const previousAssignments = get().devicePresetAssignments;
      const nextState = replacePresetDeviceAssignments(
        currentDevicePresetState(),
        presetId,
        deviceKeys
      );
      const activeDeviceKey = get().activeOutputRoute?.key ?? null;
      const previousActivePresetId = activeDeviceKey ? previousAssignments[activeDeviceKey] : null;
      const nextActivePresetId = activeDeviceKey ? nextState.assignments[activeDeviceKey] : null;

      set({ devicePresetAssignments: nextState.assignments });
      schedulePersist();

      // Only a changed assignment is an explicit request to replace the live
      // working state. Saving an unchanged checklist must preserve manual tweaks.
      if (
        activeDeviceKey &&
        nextActivePresetId === presetId &&
        previousActivePresetId !== nextActivePresetId
      ) {
        get().applyPreset(presetId);
      }
    },

    setOutputRoute: async (route) => {
      if (!get().loaded) await get().load();

      const nextRoute = normalizeAudioOutputRoute(route);
      const previousRoute = get().activeOutputRoute;
      if (!nextRoute) {
        if (previousRoute) set({ activeOutputRoute: null });
        return;
      }

      const previousDeviceState = currentDevicePresetState();
      const observedDeviceState = observeEQOutputDevice(previousDeviceState, nextRoute);
      const deviceStateChanged = observedDeviceState !== previousDeviceState;
      const activeRouteChanged =
        previousRoute?.key !== nextRoute.key ||
        previousRoute.label !== nextRoute.label ||
        previousRoute.kind !== nextRoute.kind ||
        previousRoute.nativeId !== nextRoute.nativeId ||
        previousRoute.nativeType !== nextRoute.nativeType ||
        previousRoute.selectedRouteName !== nextRoute.selectedRouteName;
      if (activeRouteChanged || deviceStateChanged) {
        set({
          ...(activeRouteChanged ? { activeOutputRoute: nextRoute } : {}),
          ...(deviceStateChanged
            ? {
                knownOutputDevices: observedDeviceState.devices,
                devicePresetAssignments: observedDeviceState.assignments,
              }
            : {}),
        });
      }
      if (deviceStateChanged) schedulePersist();

      const assignedPresetId = presetForOutputRouteTransition(
        previousRoute?.key ?? null,
        nextRoute.key,
        observedDeviceState.assignments,
        (presetId) => get().presets.some((preset) => preset.id === presetId)
      );
      if (assignedPresetId) {
        // applyPreset intentionally does not touch `enabled`, so EQ power stays global.
        get().applyPreset(assignedPresetId);
      }
    },

    _syncToNative: syncToNative,
  };
});