'use client'

import { useCallback, useEffect, useMemo, useState } from 'react'
import { Brain, Loader2, Pin, PinOff, Pencil, Plus, RotateCcw, Trash2, X } from 'lucide-react'
import { Button } from '@/components/ui/button'
import { Badge } from '@/components/ui/badge'
import { Switch } from '@/components/ui/switch'
import { EmptyState } from '@/components/ui/empty-state'
import { Skeleton } from '@/components/ui/skeleton'
import { useToast } from '@/components/ui/use-toast'
import {
  SettingsGroup,
  SettingsReveal,
  SettingsRow,
  SettingsRowEnd,
  SettingsRowNote,
  SettingsSeg,
  SettingsSelect,
  SettingsTextarea,
} from '@/components/settings/SettingsRows'
import { useCanWrite } from '@/lib/hooks/use-can-write'
import { cn, formatDateLong } from '@/lib/utils'

type Kind = 'fact' | 'preference' | 'pattern' | 'correction'
type Source = 'composer' | 'user_taught' | 'agent_learned' | 'derived'

interface AgentMemoryRow {
  id: string
  kind: Kind
  content: string
  source: Source
  source_ref: string | null
  relevance_score: number
  is_pinned: boolean
  is_active: boolean
  last_accessed_at: string | null
  created_at: string
  updated_at: string
}

const KIND_LABEL: Record<Kind, string> = {
  fact: 'Fakta',
  preference: 'Preferens',
  pattern: 'Mönster',
  correction: 'Korrigering',
}

const SOURCE_LABEL: Record<Source, string> = {
  composer: 'Inläst vid uppstart',
  user_taught: 'Du lärde mig',
  agent_learned: 'Jag noterade',
  derived: 'Härlett',
}

const KIND_FILTER: { value: 'all' | Kind; label: string }[] = [
  { value: 'all', label: 'Alla' },
  { value: 'fact', label: 'Fakta' },
  { value: 'preference', label: 'Preferenser' },
  { value: 'pattern', label: 'Mönster' },
  { value: 'correction', label: 'Korrigeringar' },
]

// The API returns errors either as a plain string (legacy/validation) or as
// the canonical { code, message } envelope; extract something renderable.
function apiErrorText(error: unknown): string | undefined {
  if (typeof error === 'string') return error
  if (error && typeof error === 'object' && 'message' in error) {
    const m = (error as { message?: unknown }).message
    return typeof m === 'string' ? m : undefined
  }
  return undefined
}

export function AgentMemoryPanel() {
  const { toast } = useToast()
  const { canWrite } = useCanWrite()

  const [rows, setRows] = useState<AgentMemoryRow[] | null>(null)
  const [includeDismissed, setIncludeDismissed] = useState(false)
  const [kindFilter, setKindFilter] = useState<'all' | Kind>('all')
  const [busyId, setBusyId] = useState<string | null>(null)
  const [editingId, setEditingId] = useState<string | null>(null)
  const [editDraft, setEditDraft] = useState('')
  const [showAdd, setShowAdd] = useState(false)
  const [newContent, setNewContent] = useState('')
  const [newKind, setNewKind] = useState<Kind>('fact')
  const [adding, setAdding] = useState(false)

  const load = useCallback(async () => {
    const params = new URLSearchParams()
    if (includeDismissed) params.set('include_dismissed', 'true')
    if (kindFilter !== 'all') params.set('kind', kindFilter)
    const res = await fetch(`/api/agent/memory?${params.toString()}`)
    const json = await res.json()
    if (!res.ok) {
      toast({ title: 'Kunde inte hämta minne', description: apiErrorText(json.error), variant: 'destructive' })
      setRows([])
      return
    }
    setRows(json.data as AgentMemoryRow[])
  }, [includeDismissed, kindFilter, toast])

  useEffect(() => { void load() }, [load])

  const counts = useMemo(() => {
    const active = rows?.filter((r) => r.is_active).length ?? 0
    const pinned = rows?.filter((r) => r.is_active && r.is_pinned).length ?? 0
    const dismissed = rows?.filter((r) => !r.is_active).length ?? 0
    return { active, pinned, dismissed }
  }, [rows])

  async function patch(id: string, body: Partial<Pick<AgentMemoryRow, 'content' | 'is_pinned' | 'is_active'>>) {
    setBusyId(id)
    try {
      const res = await fetch(`/api/agent/memory/${id}`, {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(body),
      })
      const json = await res.json()
      if (!res.ok) {
        toast({ title: 'Kunde inte uppdatera', description: apiErrorText(json.error), variant: 'destructive' })
        return
      }
      setRows((prev) => prev?.map((r) => (r.id === id ? (json.data as AgentMemoryRow) : r)) ?? null)
    } finally {
      setBusyId(null)
    }
  }

  async function addMemory() {
    if (newContent.trim().length < 2) return
    setAdding(true)
    try {
      const res = await fetch('/api/agent/memory', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ content: newContent.trim(), kind: newKind }),
      })
      const json = await res.json()
      if (!res.ok) {
        toast({ title: 'Kunde inte spara minne', description: apiErrorText(json.error), variant: 'destructive' })
        return
      }
      setRows((prev) => [json.data as AgentMemoryRow, ...(prev ?? [])])
      setNewContent('')
      setNewKind('fact')
      setShowAdd(false)
      toast({ title: 'Minne sparat' })
    } finally {
      setAdding(false)
    }
  }

  function startEdit(row: AgentMemoryRow) {
    setEditingId(row.id)
    setEditDraft(row.content)
  }

  async function saveEdit(row: AgentMemoryRow) {
    const next = editDraft.trim()
    if (next.length < 2 || next === row.content) {
      setEditingId(null)
      return
    }
    await patch(row.id, { content: next })
    setEditingId(null)
  }

  // The view wrapper in AssistantSettingsContent already provides the gap
  // under the segmented control, so the group starts flush (pt-0).
  return (
    <SettingsGroup
      label="Vad min assistent kommer ihåg"
      help={
        <>
          Bokföringsassistenten använder dessa anteckningar för att ge dig rätt råd. Fäst det som
          alltid ska vara med, redigera fel, eller dölj det som inte längre stämmer. Upp till 30
          minnen ingår i samtal per tur.
        </>
      }
      className="pt-0 first:pt-0"
    >
      {/* Toolbar row: kind filter + the add-memory entry point. */}
      <div className="flex flex-wrap items-center justify-between gap-3 border-b border-border px-1 py-3">
        <SettingsSeg
          value={kindFilter}
          onChange={setKindFilter}
          options={KIND_FILTER}
          aria-label="Filtrera minnen"
        />
        {canWrite && (
          <Button
            variant="ghost"
            size="sm"
            onClick={() => setShowAdd((v) => !v)}
            disabled={adding}
          >
            <Plus className="mr-2 h-4 w-4" />
            Lägg till minne
          </Button>
        )}
      </div>

      {canWrite && (
        <SettingsReveal open={showAdd}>
          <div className="space-y-3 py-3">
            <SettingsTextarea
              value={newContent}
              onChange={(e) => setNewContent(e.target.value)}
              placeholder="T.ex. Vi använder Stripe för B2C-betalningar; utbetalningar landar på 1930 var måndag."
              rows={3}
              maxLength={2000}
              aria-label="Nytt minne"
              className="w-full border-border"
            />
            <div className="flex flex-wrap items-center justify-between gap-3">
              <div className="flex items-center gap-2">
                <span className="text-xs text-muted-foreground">Typ</span>
                <SettingsSelect
                  value={newKind}
                  onChange={(e) => setNewKind(e.target.value as Kind)}
                  aria-label="Typ"
                >
                  {(Object.keys(KIND_LABEL) as Kind[]).map((k) => (
                    <option key={k} value={k}>{KIND_LABEL[k]}</option>
                  ))}
                </SettingsSelect>
              </div>
              <div className="flex items-center gap-2">
                <Button variant="ghost" size="sm" onClick={() => { setShowAdd(false); setNewContent('') }}>
                  Avbryt
                </Button>
                <Button size="sm" onClick={addMemory} disabled={adding || newContent.trim().length < 2}>
                  {adding ? <Loader2 className="mr-2 h-4 w-4 animate-spin" /> : null}
                  Spara
                </Button>
              </div>
            </div>
          </div>
        </SettingsReveal>
      )}

      <SettingsRow label="Visa dolda">
        <SettingsRowEnd>
          <Switch
            checked={includeDismissed}
            onCheckedChange={setIncludeDismissed}
            aria-label="Visa dolda"
          />
        </SettingsRowEnd>
      </SettingsRow>

      {/* Dynamic status stays visible; the static "how it's used" copy lives
          in the group help above. */}
      {rows && (
        <p className="px-1 pt-3">
          <SettingsRowNote className="tabular-nums">
            {counts.active} aktiva · {counts.pinned} fästa
            {includeDismissed && counts.dismissed > 0 ? ` · ${counts.dismissed} dolda` : ''}
          </SettingsRowNote>
        </p>
      )}

      {rows === null && (
        <div className="space-y-3 pt-3">
          {[0, 1, 2].map((i) => (
            <Skeleton key={i} className="h-16 w-full" />
          ))}
        </div>
      )}

      {rows && rows.length === 0 && (
        <EmptyState
          icon={Brain}
          title="Inga minnen ännu"
          description="När du lär assistenten saker (eller när den noterar saker själv med ditt godkännande) dyker de upp här."
        />
      )}

      {rows && rows.length > 0 && (
        <ul>
          {rows.map((row) => {
            const isEditing = editingId === row.id
            const isBusy = busyId === row.id
            const dimmed = !row.is_active
            return (
              <li
                key={row.id}
                className={cn(
                  'border-b border-border px-1 py-3 transition-colors',
                  dimmed && 'opacity-70',
                )}
              >
                <div className="flex items-start gap-3">
                  {canWrite && row.is_active ? (
                    <button
                      onClick={() => patch(row.id, { is_pinned: !row.is_pinned })}
                      disabled={isBusy}
                      className={cn(
                        'mt-0.5 shrink-0 rounded-md p-1.5 transition-colors duration-150',
                        row.is_pinned
                          ? 'bg-secondary text-foreground'
                          : 'text-muted-foreground hover:bg-secondary/60 hover:text-foreground',
                      )}
                      aria-label={row.is_pinned ? 'Lossa' : 'Fäst'}
                      title={row.is_pinned ? 'Lossa' : 'Fäst: säkerställer att minnet alltid skickas med'}
                    >
                      {row.is_pinned ? <Pin className="h-4 w-4 fill-current" /> : <PinOff className="h-4 w-4" />}
                    </button>
                  ) : (
                    <div className="mt-0.5 shrink-0 p-1.5">
                      {row.is_pinned && <Pin className="h-4 w-4 fill-current text-foreground" />}
                    </div>
                  )}

                  <div className="min-w-0 flex-1 space-y-2">
                    <div className="flex flex-wrap items-center gap-2">
                      <span className="text-[11px] text-muted-foreground">
                        {KIND_LABEL[row.kind]} · {SOURCE_LABEL[row.source]}
                      </span>
                      {dimmed && <Badge variant="secondary">Dold</Badge>}
                    </div>

                    {isEditing ? (
                      <SettingsTextarea
                        value={editDraft}
                        onChange={(e) => setEditDraft(e.target.value)}
                        rows={3}
                        maxLength={2000}
                        autoFocus
                        aria-label="Redigera minne"
                        className="w-full border-border"
                      />
                    ) : (
                      <p className="whitespace-pre-wrap break-words text-sm text-foreground">{row.content}</p>
                    )}

                    <div className="flex flex-wrap items-center justify-between gap-2 pt-1">
                      <p className="text-[11px] text-muted-foreground tabular-nums">
                        Skapad {formatDateLong(row.created_at)}
                        {row.updated_at !== row.created_at && ` · uppdaterad ${formatDateLong(row.updated_at)}`}
                      </p>

                      {canWrite && (
                        <div className="flex items-center gap-1">
                          {isEditing ? (
                            <>
                              <Button
                                variant="ghost"
                                size="sm"
                                onClick={() => setEditingId(null)}
                                disabled={isBusy}
                              >
                                <X className="h-4 w-4" />
                                <span className="sr-only">Avbryt</span>
                              </Button>
                              <Button
                                size="sm"
                                onClick={() => saveEdit(row)}
                                disabled={isBusy || editDraft.trim().length < 2}
                              >
                                {isBusy ? <Loader2 className="h-4 w-4 animate-spin" /> : 'Spara'}
                              </Button>
                            </>
                          ) : row.is_active ? (
                            <>
                              <Button
                                variant="ghost"
                                size="sm"
                                onClick={() => startEdit(row)}
                                disabled={isBusy}
                              >
                                <Pencil className="mr-1 h-3.5 w-3.5" />
                                Redigera
                              </Button>
                              <Button
                                variant="ghost"
                                size="sm"
                                onClick={() => patch(row.id, { is_active: false })}
                                disabled={isBusy}
                              >
                                {isBusy ? (
                                  <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
                                ) : (
                                  <Trash2 className="mr-1 h-3.5 w-3.5" />
                                )}
                                Dölj
                              </Button>
                            </>
                          ) : (
                            <Button
                              variant="ghost"
                              size="sm"
                              onClick={() => patch(row.id, { is_active: true })}
                              disabled={isBusy}
                            >
                              {isBusy ? (
                                <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
                              ) : (
                                <RotateCcw className="mr-1 h-3.5 w-3.5" />
                              )}
                              Återställ
                            </Button>
                          )}
                        </div>
                      )}
                    </div>
                  </div>
                </div>
              </li>
            )
          })}
        </ul>
      )}
    </SettingsGroup>
  )
}