import { useCallback, useEffect, useState } from "react";
import { useNavigate, useParams } from "react-router-dom";

import { getCommitDetail, getRepositoryHistory, type CommitDetail, type CommitHistoryEntry, type CommitHistoryResponse } from "../api/git_repositories";
import { EmptyState, ErrorState, LoadingState } from "../components/data-states";
import { Icon } from "../components/icon";
import { useAsyncData } from "../hooks/use-async-data";

export const GitHistoryPage = () => {
  const { projectId, repoId } = useParams<{ projectId: string; repoId: string }>();
  const navigate = useNavigate();
  const [selectedCommit, setSelectedCommit] = useState<string | null>(null);
  const [commitDetail, setCommitDetail] = useState<CommitDetail | null>(null);
  const [selectedBranch, setSelectedBranch] = useState<string>("");
  const [detailStatus, setDetailStatus] = useState<"idle" | "loading" | "ready" | "error">("idle");

  const { data: historyData, status, reload } = useAsyncData<CommitHistoryResponse>(
    async () => {
      if (!projectId || !repoId) return { commits: [], branches: [], tags: [] };
      return await getRepositoryHistory(projectId, repoId, selectedBranch || undefined, 10000);
    },
    [projectId, repoId, selectedBranch]
  );

  // Auto-select first branch when data loads
  useEffect(() => {
    if (historyData?.branches.length && !selectedBranch) {
      setSelectedBranch(historyData.branches[0]);
    }
  }, [historyData?.branches, selectedBranch]);

  const handleCommitClick = async (hash: string) => {
    if (!projectId || !repoId) return;
    setSelectedCommit(hash);
    setDetailStatus("loading");
    try {
      const detail = await getCommitDetail(projectId, repoId, hash);
      setCommitDetail(detail);
      setDetailStatus("ready");
    } catch {
      setDetailStatus("error");
    }
  };

  const handleCloseDetail = () => {
    setSelectedCommit(null);
    setCommitDetail(null);
    setDetailStatus("idle");
  };

  const formatDate = (dateStr: string) => {
    return new Date(dateStr).toLocaleString();
  };

  if (status === "loading") {
    return (
      <section className="stack">
        <LoadingState message="Loading commit history..." />
      </section>
    );
  }

  if (status === "error") {
    return (
      <section className="stack">
        <ErrorState message="Failed to load commit history" onRetry={reload} />
      </section>
    );
  }

  const commits = historyData?.commits ?? [];
  const branches = historyData?.branches ?? [];

  return (
    <section className="stack">
      <div className="page-header">
        <div>
          <h1>Commit History</h1>
          <p className="muted">{commits.length} commits</p>
        </div>
        <div className="history-actions">
          {branches.length > 0 && (
            <select
              value={selectedBranch}
              onChange={(e) => setSelectedBranch(e.target.value)}
              className="branch-selector"
            >
              {branches.map((branch) => (
                <option key={branch} value={branch}>
                  {branch}
                </option>
              ))}
            </select>
          )}
          <button
            className="secondary-button"
            onClick={() => navigate(`/projects/${projectId}/repositories`)}
            type="button"
          >
            Back to Repositories
          </button>
        </div>
      </div>

      <div className="history-container">
        <div className={`commit-list ${selectedCommit ? "with-detail" : ""}`}>
          {commits.map((commit) => (
            <div
              key={commit.hash}
              className={`commit-item ${selectedCommit === commit.hash ? "selected" : ""}`}
              onClick={() => void handleCommitClick(commit.hash)}
              role="button"
              tabIndex={0}
              onKeyDown={(e) => {
                if (e.key === "Enter" || e.key === " ") {
                  void handleCommitClick(commit.hash);
                }
              }}
            >
              <div className="commit-graph">
                <span className="graph-line" style={{ marginLeft: `${commit.graph_depth * 12}px` }}>
                  {commit.graph_symbol}
                </span>
              </div>
              <div className="commit-content">
                <div className="commit-header">
                  <span className="commit-hash">{commit.short_hash}</span>
                  {commit.refs.length > 0 && (
                    <span className="commit-refs">
                      {commit.refs.map((ref) => (
                        <span key={ref} className="ref-tag">
                          {ref}
                        </span>
                      ))}
                    </span>
                  )}
                </div>
                <p className="commit-message">{commit.message.split("\n")[0]}</p>
                <div className="commit-meta">
                  <span>{commit.author_name}</span>
                  <span className="muted">{formatDate(commit.author_date)}</span>
                </div>
              </div>
            </div>
          ))}
        </div>

        {selectedCommit && (
          <div className="commit-detail-panel">
            <div className="detail-header">
              <h3>Commit Details</h3>
              <button className="ghost-button" onClick={handleCloseDetail} type="button">
                <Icon name="close" size="sm" />
              </button>
            </div>

            {detailStatus === "loading" && <p className="muted">Loading details...</p>}
            
            {detailStatus === "error" && (
              <p>Failed to load commit details</p>
            )}

            {detailStatus === "ready" && commitDetail && (
              <div className="detail-content">
                <div className="detail-section">
                  <p className="commit-hash-full">{commitDetail.hash}</p>
                  <p className="commit-message-full">{commitDetail.message}</p>
                </div>

                <div className="detail-section">
                  <h4>Author</h4>
                  <p>{commitDetail.author_name} &lt;{commitDetail.author_email}&gt;</p>
                  <p className="muted">{formatDate(commitDetail.author_date)}</p>
                </div>

                <div className="detail-section">
                  <h4>Committer</h4>
                  <p>{commitDetail.committer_name} &lt;{commitDetail.committer_email}&gt;</p>
                  <p className="muted">{formatDate(commitDetail.committer_date)}</p>
                </div>

                <div className="detail-section">
                  <h4>Stats</h4>
                  <div className="stats-grid">
                    <div className="stat">
                      <span className="stat-value">{commitDetail.stats.files_changed}</span>
                      <span className="stat-label">Files</span>
                    </div>
                    <div className="stat additions">
                      <span className="stat-value">+{commitDetail.stats.additions}</span>
                      <span className="stat-label">Additions</span>
                    </div>
                    <div className="stat deletions">
                      <span className="stat-value">-{commitDetail.stats.deletions}</span>
                      <span className="stat-label">Deletions</span>
                    </div>
                  </div>
                </div>

                {commitDetail.parents.length > 0 && (
                  <div className="detail-section">
                    <h4>Parents</h4>
                    <div className="parent-list">
                      {commitDetail.parents.map((parent) => (
                        <span key={parent} className="parent-hash">
                          {parent.substring(0, 8)}
                        </span>
                      ))}
                    </div>
                  </div>
                )}

                {commitDetail.diff && (
                  <div className="detail-section">
                    <h4>Diff</h4>
                    <pre className="diff-content">{commitDetail.diff}</pre>
                  </div>
                )}
              </div>
            )}
          </div>
        )}
      </div>
    </section>
  );
};