import { v4 as uuid } from 'uuid'
import { create } from 'zustand'
import { validateConnection } from '../domain/compatibility'
import { allDeviceTemplates, createDeviceFromTemplate, createEmptyDiagram, incrementPortName } from '../domain/diagram'
import type { CableBundle, Catalog, Connection, Device, DeviceCategory, Diagram, Port } from '../domain/types'
import type { DiagramAccess, DiagramRepository, DiagramSummary } from '../data/DiagramRepository'
import { SupabaseDiagramRepository } from '../data/SupabaseDiagramRepository'

// This is exactly the swap the repository pattern was built for: only this
// one line changed to move off localStorage-only and onto real (locally
// self-hosted, for now) Supabase persistence — nothing else in the store or
// UI layers needed to change. LocalStorageDiagramRepository is still in the
// codebase as a reference implementation / fallback, just no longer active.
const repository: DiagramRepository = new SupabaseDiagramRepository()

// Which diagram to reopen on next launch — a session/UI preference, not app
// data, so it lives in localStorage even though the diagrams themselves are
// in Supabase now. Falls back gracefully (see loadInitialDiagram) if the
// referenced diagram no longer exists.
const LAST_DIAGRAM_ID_KEY = 'av-planner:lastDiagramId'
function getLastDiagramId(): string | null {
  try {
    return window.localStorage.getItem(LAST_DIAGRAM_ID_KEY)
  } catch {
    return null
  }
}
function setLastDiagramId(id: string): void {
  try {
    window.localStorage.setItem(LAST_DIAGRAM_ID_KEY, id)
  } catch {
    // Not essential — worst case, next launch falls back to the most
    // recently updated diagram instead of this exact one.
  }
}

async function loadMostRecent(): Promise<Diagram | null> {
  const list = await repository.list()
  if (list.length === 0) return null
  return repository.loadById(list[0].id)
}

interface DiagramStoreState {
  diagram: Diagram
  isLoaded: boolean
  /** Every diagram the current user can see, most recently updated first.
   *  Populated by refreshDiagramList — not kept live-synced on every store
   *  change, just refreshed at the moments that matter (initial load, and
   *  whenever the diagram manager UI opens or changes something). */
  diagramList: DiagramSummary[]
  /** Who owns the *currently open* diagram and what the current user can do
   *  with it — refreshed whenever the open diagram changes, not kept live
   *  (matches §8's turn-based, not realtime, collaboration model: a
   *  permission change made by the owner while you're viewing takes effect
   *  next time you load the diagram, not mid-session). Null only during the
   *  brief window before the very first diagram finishes loading. */
  access: DiagramAccess | null
  /** Set to a snapshot's id right after restoring it, meaning the live
   *  diagram data is verbatim identical to that already-existing snapshot
   *  row — see applyRestoredDiagram. `restoredDiagramUpdatedAt` is the
   *  diagram's own `updatedAt` at that moment; touch() always advances
   *  `updatedAt` on a genuine edit, so comparing the two later is a free
   *  way to tell "has anything changed since this restore" without
   *  hooking every mutating action. Both null once anything invalidates
   *  the match (an edit, or loading/switching to a diagram fresh). Used by
   *  DiagramSnapshotStore to skip writing a pointless duplicate safety
   *  snapshot when the user restores several old versions in a row without
   *  editing in between. */
  restoredFromSnapshotId: string | null
  restoredDiagramUpdatedAt: string | null
  selectedDeviceId: string | null
  selectedConnectionId: string | null
  lastConnectionError: string | null
  clearConnectionError: () => void

  /** Figures out which diagram to open on launch (last one you had open, else
   *  most recently updated, else a fresh empty one) and loads it. */
  loadInitialDiagram: () => Promise<void>
  refreshDiagramList: () => Promise<void>
  /** Creates a new diagram, makes it current, and persists it immediately
   *  (not just via the debounced autosave) so it shows up in the list right away. */
  newDiagram: (name?: string) => Promise<void>
  renameDiagram: (name: string) => void
  /** Imports diagram data under a fresh id, so it's added as a new diagram
   *  rather than risking a collision with (or silently overwriting) an
   *  existing one that happens to share the file's id. */
  importDiagram: (diagram: Diagram) => Promise<void>
  /** Applies a diagram that was already persisted by something else (the
   *  version-history "Restore" action already wrote the restored data to
   *  Supabase) — just reflects it in the currently open canvas, without
   *  re-triggering an import-style "treat this as a brand new diagram". */
  applyRestoredDiagram: (diagram: Diagram, snapshotId: string) => void
  /** Switches the active diagram to another one of the user's own. */
  switchToDiagram: (id: string) => Promise<void>
  /** Permanently deletes a diagram. If it's the currently open one, falls
   *  back to another existing diagram, or a fresh empty one if none remain. */
  deleteDiagram: (id: string) => Promise<void>

  selectDevice: (id: string | null) => void
  selectConnection: (id: string | null) => void

  addDeviceFromTemplate: (catalog: Catalog, templateId: string, position: { x: number; y: number }) => void
  updateDevicePosition: (id: string, position: { x: number; y: number }) => void
  updateDevice: (
    id: string,
    patch: Partial<Pick<Device, 'name' | 'category' | 'manufacturerId' | 'model' | 'notes' | 'cost'>>,
  ) => void
  removeDevice: (id: string) => void

  /** Returns the new port's id, so the caller can move keyboard focus to it. */
  addPort: (deviceId: string, port: Omit<Port, 'id'>) => string
  /** Inserts a copy of the port right after the original (name auto-incremented) and
   *  returns the new port's id, so the caller can move keyboard focus to it. */
  clonePort: (deviceId: string, portId: string) => string
  updatePort: (deviceId: string, portId: string, patch: Partial<Omit<Port, 'id'>>) => void
  removePort: (deviceId: string, portId: string) => void

  addConnection: (
    catalog: Catalog,
    params: {
      sourceDeviceId: string
      sourcePortId: string
      targetDeviceId: string
      targetPortId: string
      cableTypeId: string
    },
  ) => boolean
  updateConnection: (
    id: string,
    patch: Partial<Pick<Connection, 'cableTypeId' | 'distance' | 'cost' | 'label' | 'notes'>>,
  ) => void
  removeConnection: (id: string) => void

  /** Creates a new bundle containing just this one connection — the first
   *  leg of a stereo pair, snake, etc. Further legs join via
   *  addConnectionToBundle. */
  startBundle: (connectionId: string, fields: Omit<CableBundle, 'id'>) => void
  addConnectionToBundle: (connectionId: string, bundleId: string) => void
  /** Clears this connection's bundleId; deletes the bundle itself if that
   *  was its last remaining member. */
  removeConnectionFromBundle: (connectionId: string) => void
  updateBundle: (bundleId: string, patch: Partial<Omit<CableBundle, 'id'>>) => void
}

function touch(diagram: Diagram): Diagram {
  return { ...diagram, updatedAt: new Date().toISOString() }
}

/** Drops any bundle no connection references anymore — called after
 *  anything that could zero out a bundle's membership (removing a
 *  connection, or un-bundling its last remaining leg), so an empty bundle
 *  never lingers in the diagram for a user to stumble on later. */
function pruneEmptyBundles(diagram: Diagram): Diagram {
  const referencedIds = new Set(diagram.connections.map((c) => c.bundleId).filter((id): id is string => !!id))
  const bundles = diagram.bundles.filter((b) => referencedIds.has(b.id))
  return bundles.length === diagram.bundles.length ? diagram : { ...diagram, bundles }
}

export const useDiagramStore = create<DiagramStoreState>((set, get) => ({
  diagram: createEmptyDiagram(),
  isLoaded: false,
  diagramList: [],
  access: null,
  restoredFromSnapshotId: null,
  restoredDiagramUpdatedAt: null,
  selectedDeviceId: null,
  selectedConnectionId: null,
  lastConnectionError: null,
  clearConnectionError: () => set({ lastConnectionError: null }),

  loadInitialDiagram: async () => {
    const lastId = getLastDiagramId()
    const loaded = lastId ? await repository.loadById(lastId) : null
    const diagram = loaded ?? (await loadMostRecent()) ?? createEmptyDiagram()
    setLastDiagramId(diagram.id)
    const access = await repository.getAccess(diagram.id)
    set({ diagram, access, isLoaded: true, restoredFromSnapshotId: null, restoredDiagramUpdatedAt: null })
    get().refreshDiagramList()
  },

  refreshDiagramList: async () => {
    const diagramList = await repository.list()
    set({ diagramList })
  },

  newDiagram: async (name = 'Untitled Diagram') => {
    const diagram = createEmptyDiagram(name)
    setLastDiagramId(diagram.id)
    set({
      diagram,
      selectedDeviceId: null,
      selectedConnectionId: null,
      restoredFromSnapshotId: null,
      restoredDiagramUpdatedAt: null,
    })
    await repository.save(diagram)
    const access = await repository.getAccess(diagram.id)
    set({ access })
    get().refreshDiagramList()
  },

  renameDiagram: (name) => {
    set((state) => ({ diagram: touch({ ...state.diagram, name }) }))
  },

  applyRestoredDiagram: (diagram, snapshotId) => {
    set({
      diagram,
      selectedDeviceId: null,
      selectedConnectionId: null,
      restoredFromSnapshotId: snapshotId,
      restoredDiagramUpdatedAt: diagram.updatedAt,
    })
  },

  importDiagram: async (diagram) => {
    const fresh = touch({ ...diagram, id: uuid() })
    setLastDiagramId(fresh.id)
    set({
      diagram: fresh,
      selectedDeviceId: null,
      selectedConnectionId: null,
      restoredFromSnapshotId: null,
      restoredDiagramUpdatedAt: null,
    })
    await repository.save(fresh)
    const access = await repository.getAccess(fresh.id)
    set({ access })
    get().refreshDiagramList()
  },

  switchToDiagram: async (id) => {
    if (id === get().diagram.id) return
    const loaded = await repository.loadById(id)
    if (!loaded) return
    setLastDiagramId(loaded.id)
    const access = await repository.getAccess(loaded.id)
    set({
      diagram: loaded,
      access,
      selectedDeviceId: null,
      selectedConnectionId: null,
      restoredFromSnapshotId: null,
      restoredDiagramUpdatedAt: null,
    })
  },

  deleteDiagram: async (id) => {
    await repository.deleteById(id)
    if (get().diagram.id === id) {
      const next = (await loadMostRecent()) ?? createEmptyDiagram()
      setLastDiagramId(next.id)
      const access = await repository.getAccess(next.id)
      set({
        diagram: next,
        access,
        selectedDeviceId: null,
        selectedConnectionId: null,
        restoredFromSnapshotId: null,
        restoredDiagramUpdatedAt: null,
      })
    }
    get().refreshDiagramList()
  },

  selectDevice: (id) => set({ selectedDeviceId: id, selectedConnectionId: null }),
  selectConnection: (id) => set({ selectedConnectionId: id, selectedDeviceId: null }),

  addDeviceFromTemplate: (catalog, templateId, position) => {
    const { diagram } = get()
    const template = allDeviceTemplates(catalog).find((t) => t.id === templateId)
    if (!template) return
    const device = createDeviceFromTemplate(template, position)
    set({ diagram: touch({ ...diagram, devices: [...diagram.devices, device] }), selectedDeviceId: device.id })
  },

  updateDevicePosition: (id, position) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) => (d.id === id ? { ...d, position } : d)),
      }),
    }))
  },

  updateDevice: (id, patch) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) => (d.id === id ? { ...d, ...patch } : d)),
      }),
    }))
  },

  removeDevice: (id) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.filter((d) => d.id !== id),
        connections: state.diagram.connections.filter(
          (c) => c.sourceDeviceId !== id && c.targetDeviceId !== id,
        ),
      }),
      selectedDeviceId: state.selectedDeviceId === id ? null : state.selectedDeviceId,
    }))
  },

  addPort: (deviceId, port) => {
    const newId = uuid()
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) =>
          d.id === deviceId ? { ...d, ports: [...d.ports, { ...port, id: newId }] } : d,
        ),
      }),
    }))
    return newId
  },

  updatePort: (deviceId, portId, patch) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) =>
          d.id === deviceId
            ? { ...d, ports: d.ports.map((p) => (p.id === portId ? { ...p, ...patch } : p)) }
            : d,
        ),
      }),
    }))
  },

  clonePort: (deviceId, portId) => {
    const newId = uuid()
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) => {
          if (d.id !== deviceId) return d
          const index = d.ports.findIndex((p) => p.id === portId)
          if (index === -1) return d
          const source = d.ports[index]
          const clone: Port = { ...source, id: newId, name: incrementPortName(source.name) }
          return { ...d, ports: [...d.ports.slice(0, index + 1), clone, ...d.ports.slice(index + 1)] }
        }),
      }),
    }))
    return newId
  },

  removePort: (deviceId, portId) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        devices: state.diagram.devices.map((d) =>
          d.id === deviceId ? { ...d, ports: d.ports.filter((p) => p.id !== portId) } : d,
        ),
        connections: state.diagram.connections.filter(
          (c) => c.sourcePortId !== portId && c.targetPortId !== portId,
        ),
      }),
    }))
  },

  addConnection: (catalog, { sourceDeviceId, sourcePortId, targetDeviceId, targetPortId, cableTypeId }) => {
    const { diagram } = get()
    const validation = validateConnection(diagram, catalog, {
      sourceDeviceId,
      sourcePortId,
      targetDeviceId,
      targetPortId,
    })
    if (!validation.valid) {
      set({ lastConnectionError: validation.reason ?? 'Invalid connection.' })
      return false
    }
    const connection: Connection = {
      id: uuid(),
      sourceDeviceId,
      sourcePortId,
      targetDeviceId,
      targetPortId,
      cableTypeId,
    }
    set({
      diagram: touch({ ...diagram, connections: [...diagram.connections, connection] }),
      lastConnectionError: null,
      selectedConnectionId: connection.id,
      selectedDeviceId: null,
    })
    return true
  },

  updateConnection: (id, patch) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        connections: state.diagram.connections.map((c) => (c.id === id ? { ...c, ...patch } : c)),
      }),
    }))
  },

  removeConnection: (id) => {
    set((state) => ({
      diagram: touch(
        pruneEmptyBundles({
          ...state.diagram,
          connections: state.diagram.connections.filter((c) => c.id !== id),
        }),
      ),
      selectedConnectionId: state.selectedConnectionId === id ? null : state.selectedConnectionId,
    }))
  },

  startBundle: (connectionId, fields) => {
    const bundle: CableBundle = { id: uuid(), ...fields }
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        bundles: [...state.diagram.bundles, bundle],
        connections: state.diagram.connections.map((c) =>
          c.id === connectionId ? { ...c, bundleId: bundle.id } : c,
        ),
      }),
    }))
  },

  addConnectionToBundle: (connectionId, bundleId) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        connections: state.diagram.connections.map((c) => (c.id === connectionId ? { ...c, bundleId } : c)),
      }),
    }))
  },

  removeConnectionFromBundle: (connectionId) => {
    set((state) => ({
      diagram: touch(
        pruneEmptyBundles({
          ...state.diagram,
          connections: state.diagram.connections.map((c) =>
            c.id === connectionId ? { ...c, bundleId: undefined } : c,
          ),
        }),
      ),
    }))
  },

  updateBundle: (bundleId, patch) => {
    set((state) => ({
      diagram: touch({
        ...state.diagram,
        bundles: state.diagram.bundles.map((b) => (b.id === bundleId ? { ...b, ...patch } : b)),
      }),
    }))
  },
}))

// Debounced autosave: fires whenever `diagram` changes (skipped until the
// initial load completes, so we don't immediately overwrite storage with a
// blank diagram on first mount).
let saveTimeout: ReturnType<typeof setTimeout> | undefined
useDiagramStore.subscribe((state, prevState) => {
  // Skip the isLoaded:false -> true transition itself (that's the initial
  // load, not a user edit) and any tick where `diagram` didn't change.
  if (!prevState.isLoaded) return
  if (state.diagram === prevState.diagram) return
  // Defense in depth: the UI shouldn't expose any mutating control to a
  // view-only collaborator in the first place (see FlowCanvas/inspectors),
  // but skip the write here too rather than relying on RLS's silent no-op.
  if (state.access?.myPermission === 'view') return
  if (saveTimeout) clearTimeout(saveTimeout)
  saveTimeout = setTimeout(() => {
    repository.save(state.diagram).catch((err) => console.error('Autosave failed', err))
  }, 400)
})

export type { DeviceCategory }