import { Fragment, useEffect, useMemo, useRef } from 'react';

function getMediaUrl(media) {
  if (!media?.data || !media?.mimetype) return '';
  return `data:${media.mimetype};base64,${media.data}`;
}

function parseMessageText(text) {
  const rawText = String(text || '');
  const match = rawText.match(/^\*(Atendente(?: virtual)?:\s*[^*]+)\*\s*\n+/i);

  if (!match) {
    return {
      senderLabel: null,
      body: rawText,
    };
  }

  return {
    senderLabel: match[1],
    body: rawText.slice(match[0].length),
  };
}

function formatMessageTime(timestamp) {
  if (!timestamp) return '';
  const numericTimestamp = Number(timestamp);
  const date = new Date(numericTimestamp > 1000000000000 ? numericTimestamp : numericTimestamp * 1000);
  return date.toLocaleTimeString('pt-BR', { hour: '2-digit', minute: '2-digit' });
}

function getMessageDate(timestamp) {
  if (!timestamp) return null;
  const numericTimestamp = Number(timestamp);
  const date = new Date(numericTimestamp > 1000000000000 ? numericTimestamp : numericTimestamp * 1000);
  if (Number.isNaN(date.getTime())) return null;
  return date;
}

function getDateKey(timestamp) {
  const date = getMessageDate(timestamp);
  if (!date) return '';
  return date.toISOString().slice(0, 10);
}

function formatDateSeparator(timestamp) {
  const date = getMessageDate(timestamp);
  if (!date) return '';

  const today = new Date();
  const isToday =
    date.getFullYear() === today.getFullYear() &&
    date.getMonth() === today.getMonth() &&
    date.getDate() === today.getDate();

  if (isToday) return 'Hoje';

  return date.toLocaleDateString('pt-BR');
}

function DateSeparator({ label }) {
  if (!label) return null;

  return (
    <div
      style={{
        width: '100%',
        display: 'grid',
        gridTemplateColumns: '1fr auto 1fr',
        gap: '0.75rem',
        alignItems: 'center',
        color: 'var(--color-text-soft)',
        fontSize: '0.78rem',
        fontWeight: 800,
        textTransform: 'uppercase',
      }}
    >
      <span style={{ height: 1, background: 'var(--color-border)' }} />
      <span
        style={{
          border: '1px solid var(--color-border)',
          borderRadius: 999,
          padding: '0.28rem 0.7rem',
          background: 'rgba(255,255,255,0.88)',
        }}
      >
        {label}
      </span>
      <span style={{ height: 1, background: 'var(--color-border)' }} />
    </div>
  );
}

function MediaRenderer({ message, contactId, onLoadMedia, isAgent }) {
  const mediaUrl = useMemo(() => getMediaUrl(message.media), [message.media]);
  const mimetype = message.media?.mimetype || '';
  const filename = message.media?.filename || 'arquivo';

  useEffect(() => {
    if (!message.hasMedia || message.media?.data || message.mediaLoading || message.mediaError) {
      return;
    }
    onLoadMedia?.(contactId, message.id);
  }, [contactId, message, onLoadMedia]);

  if (!message.hasMedia && !message.media) return null;

  if (message.mediaLoading || (!message.media?.data && !message.mediaError)) {
    return (
      <div
        style={{
          width: 260,
          maxWidth: '100%',
          height: 150,
          borderRadius: 14,
          background: isAgent ? 'rgba(255,255,255,0.18)' : 'rgba(0,49,80,0.08)',
          display: 'grid',
          placeItems: 'center',
          color: isAgent ? '#fff' : 'var(--color-text-soft)',
          fontWeight: 700,
        }}
      >
        Carregando mídia...
      </div>
    );
  }

  if (message.mediaError) {
    return (
      <span style={{ color: isAgent ? '#fff' : 'var(--color-text-soft)', fontWeight: 700 }}>
        Não foi possível carregar a mídia.
      </span>
    );
  }

  if (mimetype.startsWith('image/')) {
    return (
      <a href={mediaUrl} target="_blank" rel="noreferrer" style={{ display: 'block' }}>
        <img
          src={mediaUrl}
          alt={filename}
          style={{
            display: 'block',
            width: 280,
            maxWidth: '100%',
            maxHeight: 340,
            objectFit: 'cover',
            borderRadius: 14,
            boxShadow: '0 14px 30px rgba(0,0,0,0.18)',
            transition: 'transform 160ms ease',
          }}
          onMouseEnter={(event) => {
            event.currentTarget.style.transform = 'scale(1.015)';
          }}
          onMouseLeave={(event) => {
            event.currentTarget.style.transform = 'scale(1)';
          }}
        />
      </a>
    );
  }

  if (mimetype.startsWith('video/')) {
    return (
      <video
        src={mediaUrl}
        controls
        style={{
          width: 320,
          maxWidth: '100%',
          borderRadius: 14,
          background: '#111',
        }}
      />
    );
  }

  if (mimetype.startsWith('audio/') || mimetype.includes('ogg')) {
    return <audio src={mediaUrl} controls style={{ width: 280, maxWidth: '100%' }} />;
  }

  return (
    <a
      href={mediaUrl}
      download={filename}
      style={{
        display: 'grid',
        gridTemplateColumns: 'auto 1fr',
        gap: '0.75rem',
        alignItems: 'center',
        padding: '0.85rem',
        borderRadius: 14,
        background: isAgent ? 'rgba(255,255,255,0.16)' : '#fff',
        color: isAgent ? '#fff' : 'var(--color-primary)',
        fontWeight: 700,
      }}
    >
      <span aria-hidden="true">📄</span>
      <span style={{ overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>{filename}</span>
    </a>
  );
}

function AttachmentPreview({ file, onRemove }) {
  if (!file) return null;
  const mediaUrl = getMediaUrl({ data: file.data, mimetype: file.type });

  return (
    <div
      style={{
        border: '1px solid var(--color-border)',
        borderRadius: 16,
        padding: '0.75rem',
        display: 'grid',
        gridTemplateColumns: 'auto 1fr auto',
        gap: '0.75rem',
        alignItems: 'center',
        background: '#fff',
      }}
    >
      {file.type?.startsWith('image/') ? (
        <img
          src={mediaUrl}
          alt={file.name}
          style={{ width: 54, height: 54, objectFit: 'cover', borderRadius: 12 }}
        />
      ) : (
        <span
          style={{
            width: 54,
            height: 54,
            borderRadius: 12,
            display: 'grid',
            placeItems: 'center',
            background: 'rgba(0,49,80,0.08)',
          }}
          aria-hidden="true"
        >
          📎
        </span>
      )}
      <div style={{ minWidth: 0 }}>
        <strong style={{ display: 'block', overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
          {file.name}
        </strong>
        <span style={{ color: 'var(--color-text-soft)', fontSize: '0.86rem' }}>{file.type || 'arquivo'}</span>
      </div>
      <button
        type="button"
        onClick={onRemove}
        title="Remover anexo"
        style={{
          border: 'none',
          borderRadius: 12,
          width: 36,
          height: 36,
          background: 'rgba(214, 40, 40, 0.1)',
          color: '#b42318',
          fontWeight: 900,
        }}
      >
        x
      </button>
    </div>
  );
}

function ContactActivity({ contact }) {
  if (!contact) {
    return null;
  }

  const status = contact.status || 'offline';
  const color = status === 'away' ? '#e5a22a' : '#dc2626';
  const label = contact.lastSeen || 'Sem atividade recente';

  return (
    <span
      style={{
        display: 'inline-flex',
        alignItems: 'center',
        gap: '0.5rem',
        color: 'var(--color-text-soft)',
      }}
    >
      <span
        aria-hidden="true"
        style={{
          width: 10,
          height: 10,
          borderRadius: 999,
          background: color,
          boxShadow: `0 0 0 3px ${color}22`,
        }}
      />
      {label}
    </span>
  );
}

export function ChatWindow({
  contact,
  messages,
  selectedArea,
  setSelectedArea,
  draft,
  setDraft,
  attachedFile,
  onAttachFile,
  onRemoveAttachedFile,
  onLoadMedia,
  onSend,
  onToggleTransfer,
  onAssumeChat,
  onReleaseChat,
  canAssumeChat = false,
  canReply = true,
  assignmentLabel,
  transferNote,
  isReplying,
  isMobile = false,
}) {
  const messagesRef = useRef(null);
  const safeContact = contact || {
    id: '',
    name: 'Nenhuma conversa ativa',
    status: 'offline',
    lastSeen: 'Aguardando fila do Omnino',
  };

  useEffect(() => {
    const container = messagesRef.current;
    if (!container) {
      return;
    }

    container.scrollTo({
      top: container.scrollHeight,
      behavior: 'auto',
    });
  }, [messages, isReplying]);

  return (
    <section
      style={{
        background: '#fff',
        border: '1px solid var(--color-border)',
        borderRadius: '28px',
        overflow: 'hidden',
        display: 'grid',
        gridTemplateRows: 'auto minmax(0, 1fr) auto',
        height: isMobile ? 'auto' : 'min(760px, calc(100vh - 190px))',
        minHeight: isMobile ? 640 : 0,
        minWidth: 0,
      }}
    >
      <header
        style={{
          padding: '1.25rem 1.5rem',
          borderBottom: '1px solid var(--color-border)',
          display: 'grid',
          gridTemplateColumns: isMobile ? '1fr' : 'minmax(0, 1fr) auto',
          gap: '1rem',
          alignItems: 'center',
        }}
      >
        <div>
          <strong style={{ display: 'block', fontSize: '1.15rem' }}>{safeContact.name}</strong>
          <ContactActivity contact={safeContact} />
        </div>

        <div
          style={{
            display: 'flex',
            gap: '0.7rem',
            flexWrap: 'wrap',
            justifyContent: isMobile ? 'stretch' : 'flex-end',
          }}
        >
          <select
            value={selectedArea}
            onChange={(event) => setSelectedArea(event.target.value)}
            disabled
            style={{
              border: '1px solid var(--color-border)',
              borderRadius: '14px',
              padding: '0.8rem 0.95rem',
              background: '#fff',
              fontWeight: 600,
            }}
          >
            <option>{selectedArea}</option>
            <option>Suporte</option>
            <option>Financeiro</option>
            <option>Comercial</option>
          </select>
          {canAssumeChat ? (
            <button
              type="button"
              onClick={() => onAssumeChat?.()}
              style={{
                border: 'none',
                borderRadius: '14px',
                padding: '0.8rem 1rem',
                background: 'linear-gradient(135deg, var(--color-primary), #0b5a86)',
                color: '#fff',
                fontWeight: 700,
              }}
            >
              Assumir atendimento
            </button>
          ) : null}
          {canReply ? (
            <button
              type="button"
              onClick={onReleaseChat}
              style={{
                border: '1px solid var(--color-border)',
                borderRadius: '14px',
                padding: '0.8rem 1rem',
                background: '#fff',
                color: 'var(--color-primary)',
                fontWeight: 700,
              }}
            >
              Sair do atendimento
            </button>
          ) : null}
          <button
            type="button"
            onClick={onToggleTransfer}
            disabled={!canReply}
            style={{
              border: 'none',
              borderRadius: '14px',
              padding: '0.8rem 1rem',
              background: 'rgba(0, 49, 80, 0.08)',
              color: 'var(--color-primary)',
              fontWeight: 700,
              opacity: canReply ? 1 : 0.55,
            }}
          >
            Transferir
          </button>
        </div>
        {transferNote ? (
          <div
            style={{
              gridColumn: '1 / -1',
              border: '1px solid rgba(0, 164, 183, 0.24)',
              borderRadius: 16,
              padding: '0.85rem 1rem',
              background: 'rgba(0, 164, 183, 0.07)',
              color: 'var(--color-text)',
              lineHeight: 1.45,
            }}
          >
            <strong style={{ display: 'block', color: 'var(--color-primary)', marginBottom: '0.25rem' }}>
              Observação da transferência
            </strong>
            {transferNote}
          </div>
        ) : null}
      </header>

      <div
        ref={messagesRef}
        style={{
          padding: '1.5rem',
          display: 'grid',
          gap: '0.9rem',
          alignContent: 'start',
          overflowY: 'auto',
          minHeight: 0,
          background:
            'radial-gradient(circle at top left, rgba(0, 164, 183, 0.06), transparent 22%), linear-gradient(180deg, rgba(245, 248, 251, 0.8), rgba(255, 255, 255, 0.95))',
        }}
      >
        {messages.map((message, index) => {
          const isAgent = message.sender === 'agent';
          const isSystem = message.sender === 'system';
          const parsedText = parseMessageText(message.text);
          const messageTime = formatMessageTime(message.timestamp);
          const dateKey = getDateKey(message.timestamp);
          const previousDateKey = index > 0 ? getDateKey(messages[index - 1]?.timestamp) : '';
          const shouldShowDateSeparator = dateKey && dateKey !== previousDateKey;
          const dateSeparator = formatDateSeparator(message.timestamp);

          if (isSystem) {
            return (
              <Fragment key={message.id}>
                {shouldShowDateSeparator ? <DateSeparator label={dateSeparator} /> : null}
                <div
                  style={{
                    justifySelf: 'center',
                    padding: '0.7rem 1rem',
                    borderRadius: '999px',
                    background: 'rgba(0, 49, 80, 0.08)',
                    color: 'var(--color-primary)',
                    fontSize: '0.88rem',
                    fontWeight: 600,
                  }}
                >
                  {message.text}
                </div>
              </Fragment>
            );
          }

          return (
            <Fragment key={message.id}>
              {shouldShowDateSeparator ? <DateSeparator label={dateSeparator} /> : null}
              <div
                style={{
                  justifySelf: isAgent ? 'end' : 'start',
                  maxWidth: isMobile ? '88%' : '72%',
                  padding: '0.95rem 1rem',
                  borderRadius: isAgent ? '18px 18px 6px 18px' : '18px 18px 18px 6px',
                  background: isAgent ? 'var(--color-primary)' : '#edf1f5',
                  color: isAgent ? '#fff' : 'var(--color-text)',
                  boxShadow: 'var(--shadow-md)',
                  display: 'grid',
                  gap: '0.65rem',
                }}
              >
                <MediaRenderer
                  message={message}
                  contactId={safeContact.id}
                  onLoadMedia={onLoadMedia}
                  isAgent={isAgent}
                />
                {parsedText.senderLabel ? (
                  <strong
                    style={{
                      display: 'block',
                      fontSize: '0.78rem',
                      lineHeight: 1.2,
                      letterSpacing: '0.02em',
                      textTransform: 'uppercase',
                      color: isAgent ? 'rgba(255,255,255,0.78)' : 'var(--color-primary)',
                    }}
                  >
                    {parsedText.senderLabel}
                  </strong>
                ) : null}
                {parsedText.body ? (
                  <span
                    style={{
                      display: 'block',
                      whiteSpace: 'pre-wrap',
                      lineHeight: 1.45,
                      overflowWrap: 'anywhere',
                    }}
                  >
                    {parsedText.body}
                  </span>
                ) : null}
                {messageTime ? (
                  <span
                    style={{
                      justifySelf: 'end',
                      fontSize: '0.72rem',
                      lineHeight: 1,
                      color: isAgent ? 'rgba(255,255,255,0.7)' : 'var(--color-text-soft)',
                    }}
                  >
                    {messageTime}
                  </span>
                ) : null}
              </div>
            </Fragment>
          );
        })}

        {messages.length === 0 ? (
          <div
            style={{
              justifySelf: 'center',
              padding: '0.8rem 1rem',
              borderRadius: 16,
              background: 'rgba(0,49,80,0.06)',
              color: 'var(--color-text-soft)',
              fontWeight: 700,
            }}
          >
            Nenhuma mensagem carregada.
          </div>
        ) : null}

        {isReplying ? (
          <div
            style={{
              justifySelf: 'start',
              padding: '0.8rem 0.95rem',
              borderRadius: '18px 18px 18px 6px',
              background: '#edf1f5',
              color: 'var(--color-text-soft)',
              fontWeight: 600,
            }}
          >
            Digitando...
          </div>
        ) : null}
      </div>

      <footer
        style={{
          padding: '1rem 1.25rem 1.25rem',
          borderTop: '1px solid var(--color-border)',
          display: 'grid',
          gridTemplateColumns: '1fr',
          gap: '0.75rem',
        }}
      >
        <AttachmentPreview file={attachedFile} onRemove={onRemoveAttachedFile} />
        {!canReply ? (
          <div
            style={{
              border: '1px solid var(--color-border)',
              borderRadius: 16,
              padding: '0.8rem 1rem',
              background: 'rgba(0, 49, 80, 0.04)',
              color: 'var(--color-text-soft)',
              fontWeight: 700,
            }}
          >
            <span style={{ display: 'block' }}>
              {canAssumeChat
                ? 'Este atendimento está na fila. Assuma para responder ou transferir.'
                : assignmentLabel || 'Este atendimento está atribuído a outro usuário.'}
            </span>
            {transferNote ? (
              <span style={{ display: 'block', marginTop: '0.45rem', color: 'var(--color-text)' }}>
                Obs: {transferNote}
              </span>
            ) : null}
          </div>
        ) : null}
        <div
          style={{
            display: 'grid',
            gridTemplateColumns: isMobile ? 'auto 1fr' : 'auto 1fr auto',
            gap: '0.75rem',
            alignItems: 'center',
          }}
        >
          <label
            title="Anexar arquivo"
            style={{
              border: '1px solid var(--color-border)',
              borderRadius: 16,
              width: 48,
              height: 48,
              display: 'grid',
              placeItems: 'center',
              background: '#fff',
              cursor: 'pointer',
              fontWeight: 900,
            }}
          >
            📎
            <input
              type="file"
              accept="image/png,image/jpeg,image/jpg,image/webp,video/mp4,video/webm,audio/mp3,audio/mpeg,audio/ogg,audio/wav,application/pdf"
              onChange={(event) => {
                onAttachFile?.(event.target.files?.[0]);
                event.target.value = '';
              }}
              style={{ display: 'none' }}
              disabled={!safeContact.id}
            />
          </label>
          <input
            type="text"
            value={draft}
            onChange={(event) => setDraft(event.target.value)}
            onKeyDown={(event) => {
              if (event.key === 'Enter') {
                onSend?.(draft);
              }
            }}
            disabled={!safeContact.id || !canReply}
            placeholder={
              !safeContact.id
                ? 'Aguardando conversa entrar em uma fila'
                : canReply
                  ? 'Escreva sua mensagem...'
                  : assignmentLabel?.includes('Aguardando resposta')
                    ? 'Aguardando resposta do cliente'
                  : canAssumeChat
                    ? 'Assuma o atendimento para responder'
                    : 'Atendimento bloqueado para resposta'
            }
            style={{
              border: '1px solid var(--color-border)',
              borderRadius: '18px',
              padding: '0.95rem 1rem',
              background: '#fff',
              outline: 'none',
              minWidth: 0,
              opacity: safeContact.id && canReply ? 1 : 0.6,
            }}
          />
          <button
            type="button"
            onClick={() => onSend?.(draft)}
            disabled={!safeContact.id || !canReply}
            style={{
              border: 'none',
              borderRadius: '18px',
              padding: '0.95rem 1.2rem',
              background: 'linear-gradient(135deg, var(--color-primary), #0b5a86)',
              color: '#fff',
              fontWeight: 700,
              gridColumn: isMobile ? '1 / -1' : 'auto',
              opacity: safeContact.id && canReply ? 1 : 0.6,
            }}
          >
            Enviar
          </button>
        </div>
      </footer>
    </section>
  );
}