import React, { useEffect, useMemo, useState } from 'react'
import { api, authUrl, setToken } from './api.js'
import PdfViewer from './components/PdfViewer.jsx'
import RegisterTable from './components/RegisterTable.jsx'
import KeyDates from './components/KeyDates.jsx'
import RiskList from './components/RiskList.jsx'
import RiskHeatmap from './components/RiskHeatmap.jsx'
import DefinedTerms from './components/DefinedTerms.jsx'
import ContractChat from './components/ContractChat.jsx'
import ContractCompare from './components/ContractCompare.jsx'
import Portfolio from './components/Portfolio.jsx'
import Login from './components/Login.jsx'

const TABS = ['Risks', 'Heatmap', 'Obligations', 'Dates', 'Glossary', 'Chat']

export default function App() {
  const [auth, setAuth] = useState('checking') // checking | required | ok
  const [authRequired, setAuthRequired] = useState(false)
  const [analysis, setAnalysis] = useState(null)
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState(null)
  const [tab, setTab] = useState('Risks')
  const [selectedClause, setSelectedClause] = useState(null)
  const [existing, setExisting] = useState([])
  const [view, setView] = useState('analyze') // analyze | portfolio
  const [showCompare, setShowCompare] = useState(false)

  useEffect(() => {
    fetch('/api/health')
      .then((r) => r.json())
      .then(async ({ auth_required }) => {
        setAuthRequired(auth_required)
        if (!auth_required) return setAuth('ok')
        const probe = await api('/api/contracts')
        setAuth(probe.ok ? 'ok' : 'required')
      })
      .catch(() => setAuth('ok'))
  }, [])

  async function refreshExisting() {
    try {
      const res = await api('/api/contracts')
      if (res.status === 401) { setToken(''); setAuth('required'); return }
      if (res.ok) setExisting(await res.json())
    } catch { /* backend down */ }
  }
  useEffect(() => { if (auth === 'ok') refreshExisting() }, [auth])

  const clauseById = useMemo(() => {
    const m = new Map()
    analysis?.clauses?.forEach((c) => m.set(c.id, c))
    return m
  }, [analysis])

  async function openExisting(id, clauseId = null) {
    setLoading(true)
    setView('analyze')
    setShowCompare(false)
    try {
      const res = await api(`/api/contracts/${id}`)
      if (res.ok) {
        const a = await res.json()
        setAnalysis(a)
        setTab('Risks')
        const clause = clauseId && a.clauses.find((c) => c.id === clauseId)
        setSelectedClause(clause || null)
      }
    } finally {
      setLoading(false)
    }
  }

  async function onUpload(file) {
    setLoading(true)
    setError(null)
    setSelectedClause(null)
    setShowCompare(false)
    setView('analyze')
    try {
      const form = new FormData()
      form.append('file', file)
      const res = await api('/api/contracts', { method: 'POST', body: form })
      if (res.status === 401) { setToken(''); setAuth('required'); return }
      if (!res.ok) {
        const body = await res.json().catch(() => ({}))
        throw new Error(body.detail || `Upload failed (${res.status})`)
      }
      setAnalysis(await res.json())
      setTab('Risks')
      refreshExisting()
    } catch (e) {
      setError(e.message)
    } finally {
      setLoading(false)
    }
  }

  const selectClause = (clauseId) => {
    const clause = clauseById.get(clauseId)
    if (clause) setSelectedClause(clause)
  }

  function signOut() {
    setToken('')
    setAnalysis(null)
    setSelectedClause(null)
    setExisting([])
    setView('analyze')
    setShowCompare(false)
    setAuth('required')
  }

  const highCount = analysis?.risks?.filter((r) => r.level === 'HIGH').length ?? 0

  if (auth === 'checking') return null
  if (auth === 'required') return <Login onSuccess={() => setAuth('ok')} />

  return (
    <div className="app">
      <header className="topbar">
        <button className="brand" title="Home" onClick={() => {
          setAnalysis(null)
          setSelectedClause(null)
          setError(null)
          setView('analyze')
          setShowCompare(false)
        }}>
          <span className="brand-mark">§</span>
          <span>
            <strong>Contract Obligation &amp; Risk Extractor</strong>
            <small>every finding traced to its source clause</small>
          </span>
        </button>
        <div className="topbar-actions">
          <button
            className={'nav-btn' + (view === 'portfolio' ? ' active' : '')}
            onClick={() => {
              setView(view === 'portfolio' ? 'analyze' : 'portfolio')
              setShowCompare(false)
            }}
          >
            {view === 'portfolio' ? '← Back' : `Portfolio${existing.length ? ` (${existing.length})` : ''}`}
          </button>
          <label className="upload-btn">
            {loading ? 'Analyzing…' : analysis ? 'Analyze another' : 'Upload contract (PDF)'}
            <input
              type="file"
              accept="application/pdf"
              disabled={loading}
              onChange={(e) => e.target.files[0] && onUpload(e.target.files[0])}
            />
          </label>
          {authRequired && (
            <button className="nav-btn signout" title="Sign out" onClick={signOut}>
              Sign out
            </button>
          )}
        </div>
      </header>

      {error && <div className="banner error">⚠ {error}</div>}
      {view === 'analyze' && analysis?.warnings?.map((w, i) => (
        <div key={i} className="banner warn">⚠ {w}</div>
      ))}

      {view === 'portfolio' && (
        <Portfolio onOpen={openExisting} onDeleted={refreshExisting} />
      )}

      {view === 'analyze' && !analysis && !loading && (
        <div className="empty">
          <div className="empty-card">
            <h1>Point it at a contract.</h1>
            <p>
              Get a structured <strong>obligation &amp; key-date register</strong> and a{' '}
              <strong>ranked risk-flag list</strong> — every item linked to the exact clause
              it came from. Click any finding to see the source highlighted in the PDF.
            </p>
            <p className="muted">
              100% open-source stack — rule engine + optional local LLM (Ollama).
              Scanned PDFs are OCR'd automatically. No contract data ever leaves this server.
            </p>
            {existing.length > 0 && (
              <div className="existing">
                <small className="muted">Already analyzed:</small>
                {existing.map((c) => (
                  <button key={c.contract_id} className="existing-btn"
                    onClick={() => openExisting(c.contract_id)}>
                    {c.filename} · {c.num_obligations} obligations · {c.num_risks} risks
                  </button>
                ))}
              </div>
            )}
          </div>
        </div>
      )}

      {view === 'analyze' && loading && (
        <div className="empty">
          <div className="empty-card">
            <h1>Reading the fine print…</h1>
            <p className="muted">parsing → clauses → classification → obligations → dates → risk baseline</p>
          </div>
        </div>
      )}

      {view === 'analyze' && analysis && !loading && (
        <div className="layout">
          <section className="left">
            <div className="summary">
              <div className="stat">
                <b>{analysis.filename}</b>
                <small>{analysis.parties.join(' · ') || 'parties unknown'}</small>
              </div>
              <div className="stat num"><b>{analysis.obligations.length}</b><small>obligations</small></div>
              <div className="stat num"><b>{analysis.key_dates.length}</b><small>key dates</small></div>
              <div className={'stat num' + (highCount ? ' danger' : '')}>
                <b>{highCount}</b><small>high risks</small>
              </div>
            </div>

            <div className="toolbar">
              <a className="tool-btn" download
                href={authUrl(`/api/contracts/${analysis.contract_id}/export.xlsx`)}>
                ⬇ Excel register
              </a>
              <a className="tool-btn" download
                href={authUrl(`/api/contracts/${analysis.contract_id}/deadlines.ics`)}>
                🗓 Add to calendar
              </a>
              {existing.length > 1 && (
                <button className="tool-btn" onClick={() => setShowCompare(true)}>
                  ⇄ Compare
                </button>
              )}
            </div>

            <nav className="tabs">
              {TABS.map((t) => (
                <button key={t} className={t === tab ? 'active' : ''} onClick={() => setTab(t)}>
                  {t}
                  {t === 'Risks' && <span className="pill">{analysis.risks.length}</span>}
                  {t === 'Obligations' && <span className="pill">{analysis.obligations.length}</span>}
                  {t === 'Dates' && <span className="pill">{analysis.key_dates.length}</span>}
                  {t === 'Glossary' && <span className="pill">{analysis.defined_terms.length}</span>}
                </button>
              ))}
            </nav>

            <div className="panel">
              {tab === 'Risks' && (
                <RiskList risks={analysis.risks} clauseById={clauseById}
                  selected={selectedClause} onSelect={selectClause} />
              )}
              {tab === 'Heatmap' && (
                <RiskHeatmap risks={analysis.risks} onSelect={selectClause} />
              )}
              {tab === 'Obligations' && (
                <RegisterTable obligations={analysis.obligations} clauseById={clauseById}
                  selected={selectedClause} onSelect={selectClause} />
              )}
              {tab === 'Dates' && (
                <KeyDates dates={analysis.key_dates} clauseById={clauseById}
                  selected={selectedClause} onSelect={selectClause} />
              )}
              {tab === 'Glossary' && (
                <DefinedTerms terms={analysis.defined_terms} onSelect={selectClause} />
              )}
              {tab === 'Chat' && (
                <ContractChat
                  contractId={analysis.contract_id}
                  onSelectClause={selectClause}
                />
              )}
            </div>
          </section>

          <section className="right">
            <PdfViewer
              fileUrl={authUrl(`/api/contracts/${analysis.contract_id}/pdf`)}
              highlight={selectedClause ? selectedClause.span : null}
            />
          </section>

          {showCompare && (
            <div className="compare-modal-backdrop" onClick={(e) => {
              if (e.target === e.currentTarget) setShowCompare(false)
            }}>
              <div className="compare-modal">
                <ContractCompare
                  currentId={analysis.contract_id}
                  currentFilename={analysis.filename}
                  existing={existing}
                  onClose={() => setShowCompare(false)}
                />
              </div>
            </div>
          )}
        </div>
      )}
    </div>
  )
}