import { useEffect, useState } from "react";
import { execSql, listColumns } from "./api";
import { DdlModal } from "./DdlModal";
import { ensureSession } from "./ObjectTree";
import { useWorkspaceStore } from "./store";

type MetaRow = Record<string, unknown>;

type TableMeta = {
  indexes: MetaRow[];
  fks: MetaRow[];
  triggers: MetaRow[];
};

const EMPTY_META: TableMeta = { indexes: [], fks: [], triggers: [] };

/** MySQL 协议族才走 information_schema 元数据（PG/Oracle 的系统目录另行适配） */
function isMysqlFamily(driver?: string) {
  return ["mysql", "mariadb", "tidb", "oceanbase", "polardb", "tdsql"].includes((driver || "").toLowerCase());
}

/** 标识符转义进 information_schema 字符串比较 */
const esc = (s: string) => s.replace(/'/g, "''");

export function SchemaPane() {
  const schema = useWorkspaceStore((s) => s.schemaView);
  const set = useWorkspaceStore((s) => s.set);
  const conn = useWorkspaceStore((s) => s.connections.find((c) => c.id === s.activeConnectionId));
  const [meta, setMeta] = useState<TableMeta>(EMPTY_META);
  /** R2-F3:DDL 查看弹窗 */
  const [showDdl, setShowDdl] = useState(false);
  const mysql = isMysqlFamily(conn?.driver);
  /** Redis 键的结构页不展示 DDL(服务端仅支持表/视图) */
  const ddlEnabled = !!conn && (conn.driver || "").toLowerCase() !== "redis";

  useEffect(() => {
    let alive = true;
    setMeta(EMPTY_META);
    if (!conn || !mysql || !schema || schema.loading || schema.error || !schema.table) return;
    (async () => {
      try {
        const sid = await ensureSession(conn);
        const db = esc(schema.database);
        const t = esc(schema.table);
        const run = (sqlText: string) => execSql(conn, sqlText, { database: schema.database, sessionId: sid, limit: 200 });
        const [ix, fk, tg] = await Promise.all([
          run(
            `SELECT INDEX_NAME AS name, IF(NON_UNIQUE=0,'UNIQUE','') AS uniq, GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX SEPARATOR ', ') AS cols FROM information_schema.STATISTICS WHERE TABLE_SCHEMA='${db}' AND TABLE_NAME='${t}' GROUP BY INDEX_NAME, NON_UNIQUE ORDER BY INDEX_NAME`,
          ),
          run(
            `SELECT CONSTRAINT_NAME AS name, COLUMN_NAME AS col, REFERENCED_TABLE_NAME AS refTable, REFERENCED_COLUMN_NAME AS refCol FROM information_schema.KEY_COLUMN_USAGE WHERE TABLE_SCHEMA='${db}' AND TABLE_NAME='${t}' AND REFERENCED_TABLE_NAME IS NOT NULL`,
          ),
          run(
            `SELECT TRIGGER_NAME AS name, ACTION_TIMING AS timing, EVENT_MANIPULATION AS event, EVENT_OBJECT_TABLE AS onTable FROM information_schema.TRIGGERS WHERE TRIGGER_SCHEMA='${db}' AND EVENT_OBJECT_TABLE='${t}'`,
          ),
        ]);
        if (alive) setMeta({ indexes: ix.rows, fks: fk.rows, triggers: tg.rows });
      } catch {
        /* 元数据不可用时静默降级：结构页至少保底显示列 */
      }
    })();
    return () => {
      alive = false;
    };
  }, [conn, mysql, schema?.database, schema?.table, schema?.loading, schema?.error]);

  if (!schema) {
    return (
      <div className="ops-empty" style={{ minHeight: 120 }}>
        <h2 style={{ fontSize: "var(--ops-text-lg)" }}>表结构</h2>
        <p>在对象树点表，或右键「查看结构」。</p>
      </div>
    );
  }

  /** E1:结构加载失败重试 —— 重新拉列元数据 */
  const retryLoad = async () => {
    if (!conn || !schema) return;
    set("schemaView", { ...schema, loading: true, error: undefined });
    try {
      const sid = await ensureSession(conn);
      const { columns } = await listColumns(conn, schema.database, schema.table, sid);
      set("schemaView", { database: schema.database, table: schema.table, columns, loading: false });
      const pkCols = columns.filter((c) => c.key === "PRI").map((c) => c.name);
      set("resultMeta", { database: schema.database, table: schema.table, pkCols });
      set("connState", "ok");
    } catch (e) {
      const msg = e instanceof Error ? e.message : String(e);
      set("schemaView", { database: schema.database, table: schema.table, columns: [], loading: false, error: msg });
      if (msg.includes("会话") || msg.toLowerCase().includes("session")) set("connState", "down");
    }
  };

  if (schema.loading) {
    return (
      <div className="px-3 py-2 text-[12.5px]" style={{ color: "var(--ops-muted)" }}>
        加载 {schema.table} 结构…
      </div>
    );
  }

  if (schema.error) {
    return (
      <div
        className="m-1.5 rounded border px-2.5 py-1.5 text-[12.5px]"
        style={{
          borderColor: "color-mix(in srgb, var(--ops-danger) 40%, var(--ops-border))",
          background: "color-mix(in srgb, var(--ops-danger) 10%, transparent)",
          color: "var(--ops-danger)",
        }}
      >
        <div>{schema.error}</div>
        <button
          type="button"
          className="mt-1 hover:underline"
          style={{ fontSize: "var(--ops-text-xs)" }}
          onClick={() => void retryLoad()}
        >
          重试
        </button>
      </div>
    );
  }

  const str = (v: unknown) => (v == null ? "" : String(v));

  return (
    <div className="flex min-h-0 flex-1 flex-col">
      <div className="ops-section-label justify-between border-b">
        <span>
          结构 · {schema.database ? `${schema.database}.` : ""}
          {schema.table}
        </span>
        <div className="flex shrink-0 items-center gap-2 normal-case tracking-normal">
          {ddlEnabled && (
            <button
              type="button"
              className="hover:underline"
              style={{ color: "var(--ops-accent)" }}
              title="查看建表语句(DDL)"
              onClick={() => setShowDdl(true)}
            >
              DDL
            </button>
          )}
          <button
            type="button"
            className="hover:underline"
            style={{ color: "var(--ops-accent)" }}
            onClick={() => set("resultTab", "data")}
          >
            回结果
          </button>
        </div>
      </div>
      <div className="min-h-0 flex-1 overflow-auto">
        {schema.columns.length === 0 ? (
          <div className="px-3 py-2 text-[12.5px]" style={{ color: "var(--ops-muted)" }}>
            无列信息
          </div>
        ) : (
          <table className="ops-grid" style={{ width: "100%" }}>
            <thead>
              <tr>
                <th style={{ width: 36 }}>#</th>
                <th>列名</th>
                <th>类型</th>
                <th style={{ width: 52 }}>键</th>
                <th style={{ width: 64 }}>可空</th>
                <th>默认值</th>
              </tr>
            </thead>
            <tbody>
              {schema.columns.map((c, i) => (
                <tr key={c.name}>
                  <td className="ops-rownum">{i + 1}</td>
                  <td>
                    {c.key === "PRI" ? <span title="主键">🔑 </span> : null}
                    {c.name}
                  </td>
                  <td className="font-mono text-[12px]">{c.type}</td>
                  <td>
                    {c.key === "PRI" ? (
                      <span
                        className="rounded px-1 font-semibold"
                        style={{
                          fontSize: "var(--ops-text-xs)",
                          color: "var(--ops-warning)",
                          background: "color-mix(in srgb, var(--ops-warning) 14%, transparent)",
                        }}
                      >
                        PRI
                      </span>
                    ) : (
                      ""
                    )}
                  </td>
                  <td>{c.nullable ? "YES" : "NO"}</td>
                  <td className="font-mono text-[12px]" style={{ color: "var(--ops-muted)" }}>
                    {c.default == null ? <span className="ops-null">NULL</span> : String(c.default)}
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        )}

        {mysql && (
          <div className="border-t" style={{ borderColor: "var(--ops-border)" }}>
            <details open className="px-3 py-1.5">              <summary className="cursor-pointer text-[12.5px] font-medium" style={{ listStyle: "none" }}>
                索引（{meta.indexes.length}）
              </summary>
              {meta.indexes.length === 0 ? (
                <div className="px-1 py-1 text-[11.5px]" style={{ color: "var(--ops-muted)" }}>无索引</div>
              ) : (
                <table className="ops-grid" style={{ width: "100%" }}>
                  <thead>
                    <tr>
                      <th>索引名</th>
                      <th style={{ width: 70 }}>唯一</th>
                      <th>列</th>
                    </tr>
                  </thead>
                  <tbody>
                    {meta.indexes.map((r, i) => (
                      <tr key={i}>
                        <td className="font-mono text-[12px]">{str(r.name)}</td>
                        <td>{r.uniq ? "✓" : ""}</td>
                        <td className="font-mono text-[12px]" style={{ color: "var(--ops-muted)" }}>{str(r.cols)}</td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              )}
            </details>

            <details open className="border-t px-3 py-1.5" style={{ borderColor: "var(--ops-border)" }}>
              <summary className="cursor-pointer text-[12.5px] font-medium" style={{ listStyle: "none" }}>
                外键（{meta.fks.length}）
              </summary>
              {meta.fks.length === 0 ? (
                <div className="px-1 py-1 text-[11.5px]" style={{ color: "var(--ops-muted)" }}>无外键</div>
              ) : (
                <table className="ops-grid" style={{ width: "100%" }}>
                  <thead>
                    <tr>
                      <th>约束名</th>
                      <th>列</th>
                      <th>引用</th>
                    </tr>
                  </thead>
                  <tbody>
                    {meta.fks.map((r, i) => (
                      <tr key={i}>
                        <td className="font-mono text-[12px]">{str(r.name)}</td>
                        <td className="font-mono text-[12px]">{str(r.col)}</td>
                        <td className="font-mono text-[12px]" style={{ color: "var(--ops-muted)" }}>
                          {str(r.refTable)}.{str(r.refCol)}
                        </td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              )}
            </details>

            <details open className="border-t px-3 py-1.5" style={{ borderColor: "var(--ops-border)" }}>
              <summary className="cursor-pointer text-[12.5px] font-medium" style={{ listStyle: "none" }}>
                触发器（{meta.triggers.length}）
              </summary>
              {meta.triggers.length === 0 ? (
                <div className="px-1 py-1 text-[11.5px]" style={{ color: "var(--ops-muted)" }}>无触发器</div>
              ) : (
                <table className="ops-grid" style={{ width: "100%" }}>
                  <thead>
                    <tr>
                      <th>触发器</th>
                      <th style={{ width: 80 }}>时机</th>
                      <th style={{ width: 80 }}>事件</th>
                    </tr>
                  </thead>
                  <tbody>
                    {meta.triggers.map((r, i) => (
                      <tr key={i}>
                        <td className="font-mono text-[12px]">{str(r.name)}</td>
                        <td>{str(r.timing)}</td>
                        <td>{str(r.event)}</td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              )}
            </details>
          </div>
        )}
      </div>
      {showDdl && conn && (
        <DdlModal conn={conn} database={schema.database} table={schema.table} onClose={() => setShowDdl(false)} />
      )}
    </div>
  );
}