import React, { useState } from "react";

/**
 * CreatePRButton — Claude-Code-on-Web parity PR creation action.
 *
 * When clicked, pushes session changes to a new branch and opens a PR.
 * Shows loading state and links to the created PR on GitHub.
 */
export default function CreatePRButton({
  repo,
  sessionId,
  branch,
  defaultBranch,
  disabled,
  onPRCreated,
}) {
  const [creating, setCreating] = useState(false);
  const [prUrl, setPrUrl] = useState(null);
  const [error, setError] = useState(null);

  const handleCreate = async () => {
    if (!repo || !branch || branch === defaultBranch) return;

    setCreating(true);
    setError(null);

    try {
      const token = localStorage.getItem("github_token");
      const headers = {
        "Content-Type": "application/json",
        ...(token ? { Authorization: `Bearer ${token}` } : {}),
      };

      const owner = repo.full_name?.split("/")[0] || repo.owner;
      const name = repo.full_name?.split("/")[1] || repo.name;

      const res = await fetch(`/api/repos/${owner}/${name}/pulls`, {
        method: "POST",
        headers,
        body: JSON.stringify({
          title: `[GitPilot] Changes from session ${sessionId ? sessionId.slice(0, 8) : branch}`,
          head: branch,
          base: defaultBranch || "main",
          body: [
            "## Summary",
            "",
            `Changes created by GitPilot AI assistant on branch \`${branch}\`.`,
            "",
            sessionId ? `Session ID: \`${sessionId}\`` : "",
            "",
            "---",
            "*This PR was generated by [GitPilot](https://github.com/ruslanmv/gitpilot).*",
          ]
            .filter(Boolean)
            .join("\n"),
        }),
      });

      const data = await res.json();
      if (!res.ok) throw new Error(data.detail || "Failed to create PR");

      const url = data.html_url || data.url;
      setPrUrl(url);
      onPRCreated?.({ pr_url: url, pr_number: data.number, branch });
    } catch (err) {
      setError(err.message);
    } finally {
      setCreating(false);
    }
  };

  if (prUrl) {
    return (
      <a
        href={prUrl}
        target="_blank"
        rel="noreferrer"
        style={styles.prLink}
      >
        <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
          <circle cx="18" cy="18" r="3" />
          <circle cx="6" cy="6" r="3" />
          <path d="M13 6h3a2 2 0 0 1 2 2v7" />
          <line x1="6" y1="9" x2="6" y2="21" />
        </svg>
        View PR on GitHub &rarr;
      </a>
    );
  }

  return (
    <div>
      <button
        type="button"
        style={{
          ...styles.btn,
          opacity: disabled || creating ? 0.55 : 1,
          cursor: disabled || creating ? "not-allowed" : "pointer",
        }}
        onClick={handleCreate}
        disabled={disabled || creating || !branch || branch === defaultBranch}
        title={
          !branch || branch === defaultBranch
            ? "Create a session branch first"
            : "Create a pull request from session changes"
        }
      >
        <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
          <circle cx="18" cy="18" r="3" />
          <circle cx="6" cy="6" r="3" />
          <path d="M13 6h3a2 2 0 0 1 2 2v7" />
          <line x1="6" y1="9" x2="6" y2="21" />
        </svg>
        {creating ? "Creating PR..." : "Create PR"}
      </button>
      {error && (
        <div style={styles.error}>{error}</div>
      )}
    </div>
  );
}

const styles = {
  btn: {
    display: "flex",
    alignItems: "center",
    gap: 6,
    height: 38,
    padding: "0 14px",
    borderRadius: 8,
    border: "1px solid rgba(16, 185, 129, 0.3)",
    background: "rgba(16, 185, 129, 0.08)",
    color: "#10B981",
    fontSize: 13,
    fontWeight: 600,
    cursor: "pointer",
    whiteSpace: "nowrap",
    transition: "background-color 0.15s",
  },
  prLink: {
    display: "flex",
    alignItems: "center",
    gap: 6,
    height: 38,
    padding: "0 14px",
    borderRadius: 8,
    background: "rgba(16, 185, 129, 0.10)",
    color: "#10B981",
    fontSize: 13,
    fontWeight: 600,
    textDecoration: "none",
    whiteSpace: "nowrap",
  },
  error: {
    fontSize: 11,
    color: "#EF4444",
    marginTop: 4,
  },
};