import { useEffect, useRef, useState } from 'react'
import { Link, useLocation, useNavigate, useParams, useSearchParams } from 'react-router-dom'
import { api, apiBlob, apiDownload, apiUpload } from '../api.js'
import CallTrace from '../components/CallTrace.jsx'
import JournalDocumentEditor from '../components/JournalDocumentEditor.jsx'
import RunLogPopup from '../components/RunLogPopup.jsx'
import { useAuth } from '../context/AuthContext.jsx'
import { useUnsavedChanges } from '../context/UnsavedChanges.jsx'
import { entryTitle, formatWhen, originLabel } from '../journal/document.js'

function navTrace(state) {
  return state?.trace || null
}

function navLog(state) {
  if (Array.isArray(state?.run_log) && state.run_log.length) return state.run_log
  const log = state?.trace?.log
  return Array.isArray(log) ? log : []
}

function downloadLocalJson(payload, filename) {
  const blob = new Blob([JSON.stringify(payload, null, 2)], { type: 'application/json;charset=utf-8' })
  const url = URL.createObjectURL(blob)
  const link = document.createElement('a')
  link.href = url
  link.download = filename
  document.body.appendChild(link)
  link.click()
  link.remove()
  URL.revokeObjectURL(url)
}

export default function JournalEditorPage() {
  const { spaceId, dayId } = useParams()
  const [params] = useSearchParams()
  const location = useLocation()
  const entryQuery = params.get('entry') || ''
  const wantDraft = params.get('draft') === '1'
  const { session, isAdmin } = useAuth()
  const navigate = useNavigate()
  const editorRef = useRef(null)
  const entryIdRef = useRef(entryQuery)
  const skipHydrate = useRef(false)
  const [day, setDay] = useState(null)
  const [entryId, setEntryId] = useState(entryQuery)
  const [title, setTitle] = useState('')
  const [body, setBody] = useState('')
  const [contentKey, setContentKey] = useState(0)
  const [versions, setVersions] = useState([])
  const [media, setMedia] = useState([])
  const [previews, setPreviews] = useState({})
  const [error, setError] = useState('')
  const [notice, setNotice] = useState('')
  const [busy, setBusy] = useState(false)
  const [savedEntryId, setSavedEntryId] = useState('')
  const [currentVersionId, setCurrentVersionId] = useState('')
  const { dirty, setDirty } = useUnsavedChanges()
  const savedRef = useRef({ title: '', body: '' })
  const [logOpen, setLogOpen] = useState(false)
  const [generationSummary, setGenerationSummary] = useState('')
  const [trace, setTrace] = useState(() => navTrace(location.state))
  const [runLog, setRunLog] = useState(() => navLog(location.state))
  const [debugOn, setDebugOn] = useState(false)

  const markClean = (nextTitle, nextBody) => {
    const titleValue = entryTitle(nextTitle || '')
    const bodyValue = nextBody || ''
    savedRef.current = { title: titleValue, body: bodyValue }
    setDirty(false)
  }

  const noteDirty = (nextTitle, nextBody) => {
    const saved = savedRef.current
    setDirty(entryTitle(nextTitle || '') !== saved.title || (nextBody || '') !== saved.body)
  }

  const showLoaded = (entry, draft) => {
    setContentKey((n) => n + 1)
    if (entry) {
      setEntryId(entry.id)
      entryIdRef.current = entry.id
      setTitle(entryTitle(entry.title || ''))
      setBody(entry.body || '')
      setVersions(entry.versions || [])
      setMedia(entry.media || [])
      setCurrentVersionId(entry.current_version_id || entry.versions?.at(-1)?.id || '')
      setGenerationSummary('')
      markClean(entry.title || '', entry.body || '')
      return
    }
    setEntryId('')
    entryIdRef.current = ''
    setTitle(entryTitle(draft?.title || ''))
    setBody(draft?.body || '')
    setVersions([])
    setMedia([])
    setSavedEntryId('')
    setCurrentVersionId('')
    setGenerationSummary(draft?.generation_summary || '')
    markClean(draft?.title || '', draft?.body || '')
  }

  const hydrate = async () => {
    const payload = await api(`/api/journal/days/${dayId}`, { token: session.token })
    setDay(payload)
    if (wantDraft) {
      showLoaded(null, payload.current_draft)
      const existing = payload.entries?.at(-1)
      if (existing?.id) {
        setSavedEntryId(existing.id)
        const entry = await api(`/api/journal/entries/${existing.id}`, { token: session.token })
        setVersions(entry.versions || [])
        setCurrentVersionId(entry.current_version_id || entry.versions?.at(-1)?.id || '')
      }
      return
    }
    const wanted = entryQuery || payload.entries.at(-1)?.id
    if (wanted) {
      const entry = await api(`/api/journal/entries/${wanted}`, { token: session.token })
      showLoaded(entry)
      setSavedEntryId(entry.id)
    } else {
      showLoaded(null, payload.current_draft)
    }
  }

  useEffect(() => {
    if (skipHydrate.current) {
      skipHydrate.current = false
      return
    }
    hydrate().catch((err) => setError(err.message))
  }, [session.token, dayId, entryQuery, wantDraft])

  useEffect(() => {
    const nextTrace = navTrace(location.state)
    const nextLog = navLog(location.state)
    if (nextTrace) setTrace(nextTrace)
    if (nextLog.length) setRunLog(nextLog)
  }, [location.state])

  useEffect(() => {
    if (!isAdmin) return undefined
    let cancelled = false
    api('/api/admin/debug', { token: session.token })
      .then((data) => {
        if (!cancelled) setDebugOn(Boolean(data.persist_enabled))
      })
      .catch(() => {
        if (!cancelled) setDebugOn(false)
      })
    api(
      `/api/admin/debug/latest?journal_day_id=${encodeURIComponent(dayId)}&purpose=journal_generate`,
      { token: session.token }
    )
      .then((payload) => {
        const run = payload?.run
        if (cancelled || !run) return
        const stored = run.trace || run.payload?.trace || null
        const log = run.run_log || run.payload?.run_log || stored?.log || []
        setTrace((current) => current || stored)
        setRunLog((current) => (current.length ? current : (Array.isArray(log) ? log : [])))
      })
      .catch(() => {})
    return () => {
      cancelled = true
    }
  }, [session.token, dayId, isAdmin])

  useEffect(() => () => setDirty(false), [setDirty])

  useEffect(() => {
    let cancelled = false
    const urls = {}
    Promise.all(
      media.map(async (item) => {
        const url = await apiBlob(`/api/journal/media/${item.id}`, { token: session.token })
        urls[item.id] = url
      })
    ).then(() => {
      if (!cancelled) setPreviews(urls)
    }).catch(() => {})
    return () => {
      cancelled = true
      Object.values(urls).forEach((url) => URL.revokeObjectURL(url))
    }
  }, [media, session.token])

  const downloadDebug = async () => {
    setError('')
    try {
      if (debugOn) {
        await apiDownload(
          `/api/admin/debug/export?format=json&journal_day_id=${encodeURIComponent(dayId)}&purpose=journal_generate`,
          { token: session.token }
        )
        return
      }
      if (!trace && !runLog.length) return
      downloadLocalJson(
        {
          kind: 'kansho.debug_export',
          version: 2,
          scope: 'journal_generate',
          journal_day_id: dayId,
          note: 'Lokale Kopie der Journal-Testspur dieses Entwurfs. Mapping-Tabelle ist ausgeschlossen.',
          run_count: 1,
          runs: [{ purpose: 'journal_generate', trace, run_log: runLog }]
        },
        'kansho-debug-journal.json'
      )
    } catch (err) {
      setError(err.message)
    }
  }

  const persist = async (nextTitle, nextBody, nextEntryId = entryIdRef.current, origin) => {
    const saved = await api('/api/journal/entries', {
      token: session.token,
      method: 'POST',
      body: {
        journal_day_id: dayId,
        entry_id: nextEntryId || undefined,
        title: entryTitle(nextTitle),
        body: nextBody,
        origin: origin || (nextEntryId ? 'user_edit' : (day?.current_draft ? 'accepted_draft' : 'user_edit')),
        source_conversation_ids: day?.current_draft?.source_conversation_ids || []
      }
    })
    entryIdRef.current = saved.id
    setEntryId(saved.id)
    setTitle(entryTitle(saved.title || ''))
    setBody(saved.body || '')
    const fresh = await api(`/api/journal/entries/${saved.id}`, { token: session.token })
    setVersions(fresh.versions || [])
    setMedia(fresh.media || [])
    setCurrentVersionId(fresh.current_version_id || fresh.versions?.at(-1)?.id || '')
    setSavedEntryId(saved.id)
    markClean(saved.title || '', saved.body || '')
    if (entryQuery !== saved.id) {
      skipHydrate.current = true
      navigate(`/journal/${spaceId}/${dayId}/entry?entry=${saved.id}`, { replace: true })
    }
    return saved
  }

  const currentMarkdown = () => {
    if (editorRef.current?.getMarkdown) return editorRef.current.getMarkdown()
    return body
  }

  const save = async (event) => {
    event.preventDefault()
    setBusy(true)
    setError('')
    setNotice('')
    try {
      const nextBody = currentMarkdown()
      if (wantDraft && savedEntryId) {
        await persist(title, nextBody, savedEntryId, 'accepted_draft')
        setNotice('Als neue Version des Eintrags übernommen.')
      } else {
        await persist(title, nextBody)
        setNotice('Gespeichert.')
      }
    } catch (err) {
      setError(err.message)
    } finally {
      setBusy(false)
    }
  }

  const saveAsNewEntry = async () => {
    setBusy(true)
    setError('')
    setNotice('')
    try {
      await persist(title, currentMarkdown(), '', 'accepted_draft')
      setNotice('Als eigenen Eintrag gespeichert.')
    } catch (err) {
      setError(err.message)
    } finally {
      setBusy(false)
    }
  }

  const revertChanges = () => {
    const saved = savedRef.current
    setTitle(saved.title)
    setBody(saved.body)
    setContentKey((n) => n + 1)
    setDirty(false)
    setNotice('Änderungen verworfen.')
  }

  const restore = async (versionId) => {
    const targetId = entryId || savedEntryId
    if (!targetId) return
    if (versionId === (currentVersionId || versions.at(-1)?.id)) return
    if (dirty && !window.confirm('Ungespeicherte Änderungen gehen verloren. Diese Version wiederherstellen?')) return
    setError('')
    setNotice('')
    try {
      const saved = await api(`/api/journal/entries/${targetId}/restore`, {
        token: session.token,
        method: 'POST',
        body: { version_id: versionId }
      })
      const fresh = await api(`/api/journal/entries/${targetId}`, { token: session.token })
      showLoaded({ ...fresh, title: saved.title, body: saved.body })
      setSavedEntryId(targetId)
      skipHydrate.current = true
      navigate(`/journal/${spaceId}/${dayId}/entry?entry=${targetId}`, { replace: true })
      setNotice('Version wiederhergestellt.')
    } catch (err) {
      setError(err.message)
    }
  }

  const remove = async () => {
    if (!entryId) return
    if (!window.confirm('Eintrag in den Papierkorb legen? Das ist noch nicht endgültig. Endgültiges Löschen geschieht später im Papierkorb.')) return
    setError('')
    setNotice('')
    try {
      await api(`/api/journal/entries/${entryId}`, { token: session.token, method: 'DELETE' })
      showLoaded(null)
      navigate(`/journal/${spaceId}/trash`)
    } catch (err) {
      setError(err.message)
    }
  }

  const upload = async (file) => {
    let currentId = entryIdRef.current
    if (!currentId) {
      const saved = await persist(title, currentMarkdown())
      currentId = saved.id
    }
    const asset = await apiUpload(`/api/journal/entries/${currentId}/media`, { token: session.token, file })
    const fresh = await api(`/api/journal/entries/${currentId}`, { token: session.token })
    setMedia(fresh.media || [])
    return asset
  }

  const removeMedia = async (mediaId) => {
    await api(`/api/journal/media/${mediaId}`, { token: session.token, method: 'DELETE' })
    setMedia((current) => current.filter((item) => item.id !== mediaId))
  }

  return (
    <section className="card journal-editor-page">
      <p className="muted">
        <Link to={`/journal/${spaceId}/${dayId}`}>Zurück zum Tag</Link>
        {day?.day?.calendar_date ? ` · ${day.day.calendar_date}` : ''}
        {isAdmin && (trace || runLog.length > 0) && (
          <>
            {' · '}
            <button type="button" className="ghost" onClick={() => setLogOpen(true)}>
              Ablauf anzeigen
            </button>
            <button type="button" className="ghost" onClick={downloadDebug} disabled={busy}>
              Debug herunterladen
            </button>
          </>
        )}
      </p>
      <h1>{wantDraft ? 'Neuer Entwurf' : 'Journal Editor'}{dirty ? ' · ungespeichert' : ''}</h1>
      <p className="lede">
        {wantDraft
          ? 'Vorschlag aus dem Gespräch. Speichern legt eine neue Version des bestehenden Eintrags an; die vorigen Fassungen bleiben in der Liste.'
          : 'Redigieren als Fließtext: Absätze und Markierungen formatieren, Bilder und Videos an die Schreibmarke setzen und verschieben. Gespeichert als Markdown. Eine neue Generierung überschreibt diese Fassung nicht still.'}
      </p>
      {error && <p className="error">{error}</p>}
      {notice && <p className="muted">{notice}</p>}
      {generationSummary && <p className="muted generation-snapshot">{generationSummary}</p>}
      <form className="stack" onSubmit={save}>
        <input
          value={title}
          onChange={(e) => {
            setTitle(e.target.value)
            noteDirty(e.target.value, currentMarkdown())
          }}
          placeholder="Überschrift"
        />
        <JournalDocumentEditor
          ref={editorRef}
          body={body}
          contentKey={contentKey}
          onChange={(next) => {
            setBody(next)
            noteDirty(title, next)
          }}
          media={media}
          previews={previews}
          onUpload={async (file) => {
            setError('')
            setBusy(true)
            try {
              return await upload(file)
            } catch (err) {
              setError(err.message)
              return null
            } finally {
              setBusy(false)
            }
          }}
          onPlaced={async () => {
            setError('')
            setBusy(true)
            try {
              await persist(title, currentMarkdown())
              setNotice('Gespeichert.')
            } catch (err) {
              setError(err.message)
            } finally {
              setBusy(false)
            }
          }}
          onRemoveMedia={removeMedia}
          disabled={busy}
        />
        <div className="row-actions">
          <button type="submit" disabled={busy}>
            {busy ? 'Speichert …' : (wantDraft && savedEntryId ? 'Als neue Version speichern' : 'Speichern')}
          </button>
          {dirty && versions.length === 0 && (
            <button type="button" className="ghost" onClick={revertChanges} disabled={busy}>
              Alle Änderungen rückgängig machen
            </button>
          )}
          {wantDraft && savedEntryId && (
            <button type="button" className="ghost" onClick={saveAsNewEntry} disabled={busy}>
              Als eigenen Eintrag speichern
            </button>
          )}
          {entryId && (
            <button type="button" className="ghost" onClick={remove}>
              In den Papierkorb
            </button>
          )}
        </div>
      </form>
      {isAdmin && trace && !logOpen && (
        <div className="journal-debug">
          <h2>Verlauf</h2>
          <CallTrace trace={trace} />
        </div>
      )}
      {versions.length > 0 && (
        <div className="stack">
          <h2>Versionen</h2>
          <ul className="stack">
            {versions.map((item) => {
              const isCurrent = item.id === (currentVersionId || versions.at(-1)?.id)
              return (
                <li key={item.id} className="row-item">
                  <span>
                    {entryTitle(item.title) || originLabel(item.origin)}
                    {' · '}
                    {originLabel(item.origin)}
                    {' · '}
                    {formatWhen(item.created)}
                    {isCurrent ? ' · Aktuell' : ''}
                  </span>
                  {isCurrent ? (
                    dirty ? (
                      <button type="button" className="ghost" onClick={revertChanges} disabled={busy}>
                        Alle Änderungen rückgängig machen
                      </button>
                    ) : null
                  ) : (
                    <button type="button" className="ghost" onClick={() => restore(item.id)} disabled={busy}>
                      Wiederherstellen
                    </button>
                  )}
                </li>
              )
            })}
          </ul>
        </div>
      )}
      <RunLogPopup
        open={logOpen}
        status="ok"
        title="Journalentwurf"
        log={runLog.length ? runLog : (trace?.log || [])}
        trace={trace}
        showTrace={isAdmin}
        onClose={() => setLogOpen(false)}
      />
    </section>
  )
}