"""
Query tab — SQL database interaction with editor, results grid, and export.
"""

import csv
import io
import time
import threading
from tkinter import ttk, filedialog

import customtkinter as ctk

from core.i18n import t
from core.icons import icon_text
from core.sql_client import SQLClient


class QueryTab(ctk.CTkFrame):
    def __init__(self, master, store):
        super().__init__(master, fg_color="transparent")
        self._current_alias: str | None = None
        self.store = store
        self._client: SQLClient | None = None
        self._results: list[list] = []
        self._columns: list[str] = []
        self._executing = False

        self._build_ui()

    # ── UI construction ────────────────────────────────────────────

    def _build_ui(self):
        # === Database selector row ===
        db_row = ctk.CTkFrame(self, fg_color="transparent")
        db_row.pack(fill="x", padx=10, pady=(10, 5))

        ctk.CTkLabel(db_row, text=t("query_database"), anchor="w").pack(
            side="left", padx=(0, 8)
        )

        self._db_var = ctk.StringVar(value="")
        self._db_combo = ctk.CTkComboBox(
            db_row,
            variable=self._db_var,
            values=[],
            width=220,
            command=self._on_db_selected,
        )
        self._db_combo.pack(side="left")

        # === SQL Editor ===
        editor_frame = ctk.CTkFrame(self, fg_color="transparent")
        editor_frame.pack(fill="both", expand=True, padx=10, pady=5, side="top")
        # Give editor roughly 1/3 of space
        editor_frame.pack_configure(expand=False)

        self._editor = ctk.CTkTextbox(
            editor_frame,
            font=ctk.CTkFont(family="Consolas", size=13),
            height=160,
            wrap="none",
        )
        self._editor.pack(fill="both", expand=True)
        self._editor.insert("0.0", t("query_editor_placeholder"))
        self._editor.bind("<FocusIn>", self._on_editor_focus)

        # Bind keyboard shortcuts
        self._editor.bind("<F5>", lambda e: self._execute_query())
        self._editor.bind("<Control-Return>", lambda e: self._execute_query())

        # === Button row ===
        btn_row = ctk.CTkFrame(self, fg_color="transparent")
        btn_row.pack(fill="x", padx=10, pady=5)

        self._exec_btn = ctk.CTkButton(
            btn_row,
            text=icon_text("execute", t("query_execute")),
            command=self._execute_query,
            width=130,
            fg_color="#2563eb",
            hover_color="#1d4ed8",
        )
        self._exec_btn.pack(side="left", padx=(0, 6))

        self._clear_btn = ctk.CTkButton(
            btn_row,
            text=icon_text("clear", t("query_clear")),
            command=self._clear_all,
            width=80,
            fg_color="#6b7280",
            hover_color="#4b5563",
        )
        self._clear_btn.pack(side="left", padx=(0, 6))

        self._export_btn = ctk.CTkButton(
            btn_row,
            text=icon_text("save", t("query_export_csv")),
            command=self._export_csv,
            width=110,
            fg_color="#059669",
            hover_color="#047857",
        )
        self._export_btn.pack(side="left")

        # === Results area (Treeview) ===
        results_frame = ctk.CTkFrame(self, fg_color="transparent")
        results_frame.pack(fill="both", expand=True, padx=10, pady=(5, 5))

        # Horizontal scrollbar
        self._tree_xscroll = ttk.Scrollbar(results_frame, orient="horizontal")
        self._tree_xscroll.pack(side="bottom", fill="x")

        # Vertical scrollbar
        self._tree_yscroll = ttk.Scrollbar(results_frame, orient="vertical")
        self._tree_yscroll.pack(side="right", fill="y")

        self._tree = ttk.Treeview(
            results_frame,
            show="headings",
            xscrollcommand=self._tree_xscroll.set,
            yscrollcommand=self._tree_yscroll.set,
        )
        self._tree.pack(fill="both", expand=True)

        self._tree_xscroll.config(command=self._tree.xview)
        self._tree_yscroll.config(command=self._tree.yview)

        # === Status bar ===
        self._status_label = ctk.CTkLabel(
            self,
            text="",
            anchor="w",
            font=ctk.CTkFont(size=12),
            text_color="#9ca3af",
        )
        self._status_label.pack(fill="x", padx=12, pady=(0, 8))

    # ── Editor placeholder logic ───────────────────────────────────

    def _on_editor_focus(self, event=None):
        content = self._editor.get("0.0", "end").strip()
        placeholder = t("query_editor_placeholder")
        if content == placeholder:
            self._editor.delete("0.0", "end")

    # ── Server / database connection ───────────────────────────────

    def set_server(self, alias: str | None):
        """Called when user selects a server in the sidebar."""
        self._current_alias = alias
        self._disconnect()
        self._clear_results()
        self._set_status("")

        if not alias:
            self._db_combo.configure(values=[])
            self._db_var.set("")
            return

        self._set_status(f"Connecting to {alias}...")
        threading.Thread(
            target=self._connect_and_list_dbs,
            args=(alias,),
            daemon=True,
        ).start()

    def _connect_and_list_dbs(self, alias: str):
        """Background: create SQLClient, fetch database list."""
        try:
            server = self.store.get_server(alias)
            if not server:
                self._schedule(self._set_status, t("query_error"), error=True)
                return

            client = SQLClient(server)
            databases = client.list_databases()

            def _update():
                if self._current_alias != alias:
                    return  # switched away
                self._client = client
                self._db_combo.configure(values=databases)
                if databases:
                    self._db_var.set(databases[0])
                    self._switch_database(databases[0])
                self._set_status("OK")

            self._schedule(_update)
        except Exception as exc:
            self._schedule(self._set_status, str(exc), error=True)

    def _on_db_selected(self, value: str):
        if value:
            self._switch_database(value)

    def _switch_database(self, db_name: str):
        """Switch active database on the current client."""
        if not self._client:
            return
        try:
            self._client.use_database(db_name)
            self._set_status(f"Database: {db_name}")
        except Exception as exc:
            self._set_status(str(exc), error=True)

    def _disconnect(self):
        if self._client:
            try:
                self._client.close()
            except Exception:
                pass
            self._client = None

    # ── Query execution ────────────────────────────────────────────

    def _execute_query(self):
        """Run the SQL query in a background thread."""
        if self._executing or not self._client:
            return

        sql = self._editor.get("0.0", "end").strip()
        if not sql or sql == t("query_editor_placeholder"):
            return

        self._executing = True
        self._exec_btn.configure(state="disabled")
        self._set_status("Executing...")

        threading.Thread(
            target=self._run_query,
            args=(sql,),
            daemon=True,
        ).start()

    def _run_query(self, sql: str):
        """Background thread: execute SQL, measure time, post results."""
        start = time.perf_counter()
        try:
            columns, rows = self._client.execute(sql)
            elapsed = time.perf_counter() - start

            def _update():
                self._columns = columns
                self._results = rows
                self._populate_tree(columns, rows)
                row_count = len(rows)
                self._set_status(
                    t("query_status_rows").format(
                        rows=row_count, time=f"{elapsed:.3f}"
                    )
                )
                self._executing = False
                self._exec_btn.configure(state="normal")

            self._schedule(_update)
        except Exception as exc:
            elapsed = time.perf_counter() - start

            def _update_err():
                self._set_status(
                    f"{t('query_error')}: {exc}", error=True
                )
                self._executing = False
                self._exec_btn.configure(state="normal")

            self._schedule(_update_err)

    # ── Treeview population ────────────────────────────────────────

    def _populate_tree(self, columns: list[str], rows: list[list]):
        """Clear and populate the Treeview with query results."""
        self._tree.delete(*self._tree.get_children())

        if not columns:
            self._tree["columns"] = ()
            return

        self._tree["columns"] = columns
        for col in columns:
            self._tree.heading(col, text=col, anchor="w")
            self._tree.column(col, width=120, minwidth=60, anchor="w")

        for row in rows:
            display = [str(v) if v is not None else "NULL" for v in row]
            self._tree.insert("", "end", values=display)

    def _clear_results(self):
        """Remove all rows and columns from the Treeview."""
        self._tree.delete(*self._tree.get_children())
        self._tree["columns"] = ()
        self._columns = []
        self._results = []

    # ── Button actions ─────────────────────────────────────────────

    def _clear_all(self):
        """Clear editor content and results."""
        self._editor.delete("0.0", "end")
        self._clear_results()
        self._set_status("")

    def _export_csv(self):
        """Export current results to a CSV file via save dialog."""
        if not self._columns or not self._results:
            return

        path = filedialog.asksaveasfilename(
            defaultextension=".csv",
            filetypes=[("CSV files", "*.csv"), ("All files", "*.*")],
            title=t("query_export_csv"),
        )
        if not path:
            return

        try:
            with open(path, "w", newline="", encoding="utf-8") as f:
                writer = csv.writer(f)
                writer.writerow(self._columns)
                for row in self._results:
                    writer.writerow(
                        [str(v) if v is not None else "" for v in row]
                    )
            self._set_status(f"Exported {len(self._results)} rows to {path}")
        except Exception as exc:
            self._set_status(f"{t('query_error')}: {exc}", error=True)

    # ── Status bar ─────────────────────────────────────────────────

    def _set_status(self, text: str, error: bool = False):
        color = "#ef4444" if error else "#9ca3af"
        self._status_label.configure(text=text, text_color=color)

    # ── Thread-safe scheduling ─────────────────────────────────────

    def _schedule(self, func, *args, **kwargs):
        """Schedule a function to run on the main (tkinter) thread."""
        self.after(0, lambda: func(*args, **kwargs))