import { useState, useEffect } from "react";
import { useNavigate } from "react-router-dom";
import { fetchConversations, ConversationSummary } from "../api";

export function ReplayListPage() {
  const navigate = useNavigate();
  const [page, setPage] = useState(1);
  const [perPage] = useState(20);
  const [total, setTotal] = useState(0);
  const [conversations, setConversations] = useState<ConversationSummary[]>([]);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    setIsLoading(true);
    setError(null);
    fetchConversations(page, perPage)
      .then((result) => {
        setConversations(result.conversations);
        setTotal(result.total);
      })
      .catch((err: Error) => setError(err.message))
      .finally(() => setIsLoading(false));
  }, [page, perPage]);

  const totalPages = Math.max(1, Math.ceil(total / perPage));

  function formatDate(iso: string): string {
    try {
      return new Date(iso).toLocaleString();
    } catch {
      return iso;
    }
  }

  function formatCost(usd: number): string {
    return `$${usd.toFixed(2)}`;
  }

  return (
    <div className="page-container">
      <div className="page-header" style={{ display: "flex", justifyContent: "space-between", alignItems: "flex-end", marginBottom: "2rem" }}>
        <div>
          <h2>Conversation Replay</h2>
          <p>Review autonomous agent sessions and audit MCP action execution trails.</p>
        </div>
      </div>

      {error ? (
        <div style={{ padding: "3rem", textAlign: "center", color: "var(--text-secondary)" }}>
          <p style={{ fontSize: "1.125rem", fontWeight: 600, color: "var(--brand-accent)" }}>Failed to load conversations</p>
          <p style={{ marginTop: "0.5rem" }}>{error}</p>
          <button onClick={() => setPage(1)} className="btn btn-secondary" style={{ marginTop: "1rem" }}>Retry</button>
        </div>
      ) : isLoading ? (
        <div style={{ backgroundColor: "var(--bg-surface)", borderRadius: "var(--radius-xl)", overflow: "hidden", border: "1px solid var(--border-light)", padding: "2rem" }}>
          {[1, 2, 3, 4, 5].map(i => (
            <div key={i} className="skeleton-box" style={{ height: "60px", marginBottom: "1rem", borderRadius: "8px" }}>
              <div className="skeleton-text" style={{ width: "30%", height: "14px", margin: "12px 16px" }}></div>
            </div>
          ))}
        </div>
      ) : conversations.length === 0 ? (
        <div style={{ padding: "3rem", textAlign: "center", color: "var(--text-secondary)" }}>
          <p style={{ fontSize: "1.125rem", fontWeight: 600 }}>No conversations yet</p>
          <p style={{ marginTop: "0.5rem" }}>Start a chat session to see conversations here.</p>
        </div>
      ) : (
        <div style={{ backgroundColor: "var(--bg-surface)", borderRadius: "var(--radius-xl)", overflow: "hidden", border: "1px solid var(--border-light)" }}>
          <table style={{ width: "100%", borderCollapse: "collapse", textAlign: "left" }}>
            <thead>
              <tr style={{ backgroundColor: "var(--bg-surface-inner)", borderBottom: "1px solid var(--border-light)" }}>
                <th style={{ padding: "1rem 1.5rem", fontSize: "0.75rem", textTransform: "uppercase", color: "var(--text-secondary)", fontWeight: 600 }}>Thread</th>
                <th style={{ padding: "1rem 1.5rem", fontSize: "0.75rem", textTransform: "uppercase", color: "var(--text-secondary)", fontWeight: 600 }}>Created</th>
                <th style={{ padding: "1rem 1.5rem", fontSize: "0.75rem", textTransform: "uppercase", color: "var(--text-secondary)", fontWeight: 600 }}>Last Activity</th>
                <th style={{ padding: "1rem 1.5rem", fontSize: "0.75rem", textTransform: "uppercase", color: "var(--text-secondary)", fontWeight: 600 }}>Status</th>
                <th style={{ padding: "1rem 1.5rem", fontSize: "0.75rem", textTransform: "uppercase", color: "var(--text-secondary)", fontWeight: 600 }}>Cost</th>
              </tr>
            </thead>
            <tbody>
              {conversations.map((c, i) => (
                <tr
                  key={c.thread_id}
                  onClick={() => navigate(`/replay/${c.thread_id}`)}
                  style={{
                    borderBottom: i === conversations.length - 1 ? "none" : "1px solid var(--border-light)",
                    cursor: "pointer",
                    transition: "background-color 0.2s"
                  }}
                  className="replay-row-hover"
                >
                  <td style={{ padding: "1.25rem 1.5rem" }}>
                    <div style={{ fontWeight: 600, color: "var(--text-primary)", fontSize: "0.9375rem", fontFamily: "monospace" }}>{c.thread_id}</div>
                  </td>
                  <td style={{ padding: "1.25rem 1.5rem", fontSize: "0.875rem", color: "var(--text-secondary)" }}>
                    {formatDate(c.created_at)}
                  </td>
                  <td style={{ padding: "1.25rem 1.5rem", fontSize: "0.875rem", color: "var(--text-secondary)" }}>
                    {formatDate(c.last_activity)}
                  </td>
                  <td style={{ padding: "1.25rem 1.5rem" }}>
                    <span style={{
                      fontSize: "0.75rem",
                      padding: "4px 10px",
                      borderRadius: "6px",
                      fontWeight: 600,
                      backgroundColor: c.status === "resolved" ? "#DEF7EC" : c.status === "escalated" ? "#FDE8E8" : "var(--bg-hover)",
                      color: c.status === "resolved" ? "#03543F" : c.status === "escalated" ? "#9B1C1C" : "var(--text-secondary)",
                    }}>
                      {c.status ?? "active"}
                    </span>
                  </td>
                  <td style={{ padding: "1.25rem 1.5rem", fontSize: "0.875rem", color: "var(--text-secondary)" }}>
                    {c.total_tokens.toLocaleString()} tokens / {formatCost(c.total_cost_usd)}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>

          <div style={{ padding: "1.25rem 1.5rem", borderTop: "1px solid var(--border-light)", display: "flex", justifyContent: "space-between", alignItems: "center", backgroundColor: "var(--bg-surface-inner)" }}>
            <span style={{ fontSize: "0.875rem", color: "var(--text-secondary)" }}>
              Showing {(page - 1) * perPage + 1}-{Math.min(page * perPage, total)} of {total} sessions
            </span>
            <div style={{ display: "flex", gap: "0.5rem" }}>
              <button
                onClick={(e) => { e.stopPropagation(); setPage(p => Math.max(1, p - 1)) }}
                disabled={page === 1}
                className="btn btn-secondary"
              >
                Previous
              </button>
              <button
                onClick={(e) => { e.stopPropagation(); setPage(p => Math.min(totalPages, p + 1)) }}
                disabled={page >= totalPages}
                className="btn btn-secondary"
              >
                Next
              </button>
            </div>
          </div>
        </div>
      )}
      <style>{`
        .replay-row-hover:hover {
          background-color: var(--bg-hover) !important;
        }
      `}</style>
    </div>
  );
}