"""
S3 tab — bucket/object browser with upload, download, delete actions.
Supports drag-and-drop from OS file manager for upload.
"""

import os
import sys
import tempfile
import threading
from tkinter import ttk, filedialog

import customtkinter as ctk
from core.s3_client import S3Client
from core.i18n import t
from core.icons import icon_text, make_icon_button
from gui.tabs.query_tab import apply_dark_scrollbar_style


def _human_size(size_bytes: int) -> str:
    """Format bytes to human-readable string."""
    if size_bytes < 1024:
        return f"{size_bytes} B"
    for unit in ("KB", "MB", "GB", "TB"):
        size_bytes /= 1024
        if size_bytes < 1024:
            return f"{size_bytes:.1f} {unit}"
    return f"{size_bytes:.1f} PB"


def _setup_drop(widget, callback):
    """Setup OS drag-and-drop onto a widget. Cross-platform with graceful fallback."""
    if sys.platform == "win32":
        try:
            import windnd
            windnd.hook_dropfiles(widget, func=callback)
            return True
        except Exception:
            pass
    # tkinterdnd2 fallback (works on Linux/macOS if installed)
    try:
        widget.drop_target_register("DND_Files")
        widget.dnd_bind("<<Drop>>", lambda e: callback(_parse_dnd_paths(e.data)))
        return True
    except Exception:
        pass
    return False


def _parse_dnd_paths(data: str) -> list[str]:
    """Parse tkinterdnd2 drop data into list of file paths."""
    paths = []
    # tkinterdnd2 wraps paths with spaces in braces: {C:/path with spaces/file.txt}
    i = 0
    while i < len(data):
        if data[i] == '{':
            end = data.index('}', i)
            paths.append(data[i + 1:end])
            i = end + 2  # skip } and space
        elif data[i] == ' ':
            i += 1
        else:
            end = data.find(' ', i)
            if end == -1:
                end = len(data)
            paths.append(data[i:end])
            i = end + 1
    return paths


class S3Tab(ctk.CTkFrame):
    def __init__(self, master, store):
        super().__init__(master, fg_color="transparent")
        self.store = store
        self._current_alias: str | None = None
        self._client: S3Client | None = None
        self._current_bucket: str = ""
        self._current_prefix: str = ""
        self._nav_stack: list[str] = []
        self._dnd_active = False

        self._build_ui()

    def _build_ui(self):
        apply_dark_scrollbar_style()

        # ── Header ──
        header = ctk.CTkFrame(self, fg_color="transparent")
        header.pack(fill="x", padx=15, pady=(15, 5))

        self._title_label = ctk.CTkLabel(
            header, text=t("s3_objects"),
            font=ctk.CTkFont(size=18, weight="bold"),
        )
        self._title_label.pack(side="left")

        self._status_label = ctk.CTkLabel(
            header, text="", font=ctk.CTkFont(size=12),
            text_color="#9ca3af",
        )
        self._status_label.pack(side="left", padx=(15, 0))

        # Buttons
        btn_frame = ctk.CTkFrame(header, fg_color="transparent")
        btn_frame.pack(side="right")

        self._back_btn = make_icon_button(
            btn_frame, "back", t("s3_back"), width=80,
            command=self._go_back, state="disabled",
        )
        self._back_btn.pack(side="left", padx=(0, 5))

        self._refresh_btn = make_icon_button(
            btn_frame, "refresh", t("s3_refresh"), width=100,
            command=self._refresh,
        )
        self._refresh_btn.pack(side="left", padx=(0, 5))

        self._upload_btn = make_icon_button(
            btn_frame, "upload", t("s3_upload"), width=100,
            command=self._upload,
        )
        self._upload_btn.pack(side="left", padx=(0, 5))

        self._download_btn = make_icon_button(
            btn_frame, "download", t("s3_download"), width=110,
            command=self._download,
        )
        self._download_btn.pack(side="left", padx=(0, 5))

        self._delete_btn = make_icon_button(
            btn_frame, "delete", t("s3_delete"), width=100,
            fg_color="#dc2626", hover_color="#b91c1c",
            command=self._delete,
        )
        self._delete_btn.pack(side="left")

        # ── Bucket selector row ──
        bucket_frame = ctk.CTkFrame(self, fg_color="transparent")
        bucket_frame.pack(fill="x", padx=15, pady=(5, 5))

        ctk.CTkLabel(bucket_frame, text=t("s3_bucket"),
                      font=ctk.CTkFont(size=12, weight="bold")).pack(side="left", padx=(0, 5))

        self._bucket_var = ctk.StringVar(value="")
        self._bucket_menu = ctk.CTkOptionMenu(
            bucket_frame, variable=self._bucket_var, values=[""],
            width=200, command=self._on_bucket_change,
        )
        self._bucket_menu.pack(side="left", padx=(0, 15))

        # Path display
        self._path_label = ctk.CTkLabel(
            bucket_frame, text="/", font=ctk.CTkFont(family="Consolas", size=12),
            text_color="#60a5fa",
        )
        self._path_label.pack(side="left", fill="x", expand=True)

        # ── Progress bar (hidden by default) ──
        self._progress_frame = ctk.CTkFrame(self, fg_color="transparent")
        # Don't pack yet — shown only during transfer

        self._progress_label = ctk.CTkLabel(
            self._progress_frame, text="", font=ctk.CTkFont(size=11),
            text_color="#9ca3af",
        )
        self._progress_label.pack(side="left", padx=(0, 10))

        self._progress_bar = ctk.CTkProgressBar(self._progress_frame, width=300, height=14)
        self._progress_bar.set(0)
        self._progress_bar.pack(side="left", fill="x", expand=True)

        self._progress_pct = ctk.CTkLabel(
            self._progress_frame, text="0%", font=ctk.CTkFont(size=11, weight="bold"),
            text_color="#60a5fa", width=45,
        )
        self._progress_pct.pack(side="left", padx=(10, 0))

        self._transfer_bytes = 0
        self._transfer_total = 0

        # ── Treeview for objects ──
        self._tree_frame = ctk.CTkFrame(self, fg_color="#1e1e1e", corner_radius=8)
        self._tree_frame.pack(fill="both", expand=True, padx=15, pady=(5, 15))

        columns = ("name", "size", "modified")
        self._tree = ttk.Treeview(
            self._tree_frame, columns=columns, show="headings",
            selectmode="browse", style="Dark.Treeview",
        )
        self._tree.heading("name", text=t("s3_col_name"))
        self._tree.heading("size", text=t("s3_col_size"))
        self._tree.heading("modified", text=t("s3_col_modified"))
        self._tree.column("name", width=400, minwidth=200)
        self._tree.column("size", width=100, minwidth=80, anchor="e")
        self._tree.column("modified", width=180, minwidth=120)

        scrollbar = ttk.Scrollbar(self._tree_frame, orient="vertical",
                                   command=self._tree.yview,
                                   style="Dark.Vertical.TScrollbar")
        self._tree.configure(yscrollcommand=scrollbar.set)

        self._tree.pack(side="left", fill="both", expand=True)
        scrollbar.pack(side="right", fill="y")

        # Double-click to enter prefix (folder) or download file
        self._tree.bind("<Double-1>", self._on_double_click)

        # Dark treeview style
        style = ttk.Style()
        style.configure("Dark.Treeview",
                         background="#2b2b2b", foreground="#e5e5e5",
                         fieldbackground="#2b2b2b", borderwidth=0, rowheight=26)
        style.configure("Dark.Treeview.Heading",
                         background="#333333", foreground="#e5e5e5",
                         borderwidth=0, relief="flat")
        style.map("Dark.Treeview",
                   background=[("selected", "#1e3a5f")],
                   foreground=[("selected", "#ffffff")])

        # ── Drop zone overlay (shown when no files / as hint) ──
        self._drop_hint = ctk.CTkLabel(
            self._tree_frame,
            text=t("s3_drop_hint"),
            font=ctk.CTkFont(size=14),
            text_color="#6b7280",
        )

        # Setup OS drag-and-drop on the treeview area
        self.after(200, self._init_dnd)

    def _init_dnd(self):
        """Initialize drag-and-drop after widget is mapped."""
        try:
            self._dnd_active = _setup_drop(self._tree, self._on_files_dropped)
            if not self._dnd_active:
                # Try on the frame too
                self._dnd_active = _setup_drop(self._tree_frame, self._on_files_dropped)
        except Exception:
            self._dnd_active = False

    def _on_files_dropped(self, files):
        """Handle files dropped from OS file manager."""
        if not self._client or not self._current_bucket:
            return
        # windnd gives list of bytes on Windows
        paths = []
        for f in files:
            if isinstance(f, bytes):
                paths.append(f.decode("utf-8", errors="replace"))
            else:
                paths.append(str(f))
        paths = [p for p in paths if os.path.isfile(p)]
        if not paths:
            return
        self._upload_files(paths)

    def _show_progress(self, label: str, total_bytes: int):
        """Show and reset the progress bar."""
        self._transfer_bytes = 0
        self._transfer_total = max(total_bytes, 1)
        self._progress_bar.set(0)
        self._progress_pct.configure(text="0%")
        self._progress_label.configure(text=label)
        self._progress_frame.pack(fill="x", padx=15, pady=(2, 2),
                                   before=self._tree_frame)

    def _hide_progress(self):
        """Hide the progress bar."""
        self._progress_frame.pack_forget()

    def _on_progress(self, chunk_bytes: int):
        """Called from transfer thread — schedule GUI update."""
        self._transfer_bytes += chunk_bytes
        self.after(0, self._update_progress)

    def _update_progress(self):
        """Update progress bar on GUI thread."""
        if self._transfer_total <= 0:
            return
        ratio = min(self._transfer_bytes / self._transfer_total, 1.0)
        self._progress_bar.set(ratio)
        pct = int(ratio * 100)
        self._progress_pct.configure(text=f"{pct}%")
        size_str = f"{_human_size(self._transfer_bytes)} / {_human_size(self._transfer_total)}"
        label = self._progress_label.cget("text").split(" — ")[0]
        self._progress_label.configure(text=f"{label} — {size_str}")

    def _on_transfer_status(self, message: str):
        """Called from transfer thread with retry/status info."""
        # Reset progress on retry (boto3 restarts the transfer)
        self._transfer_bytes = 0
        self.after(0, lambda: self._status_label.configure(text=message))

    def _upload_files(self, paths: list[str]):
        """Upload multiple files to current prefix."""
        if not self._client or not self._current_bucket:
            return
        total_files = len(paths)
        total_bytes = sum(os.path.getsize(p) for p in paths if os.path.isfile(p))
        label = (t("s3_uploading_n").format(count=total_files) if total_files > 1
                 else t("s3_uploading"))
        self._status_label.configure(text=label)
        self._show_progress(label, total_bytes)

        def _do():
            ok_count = 0
            for path in paths:
                filename = os.path.basename(path)
                key = self._current_prefix + filename
                if self._client.upload_file(
                        path, self._current_bucket, key,
                        progress_cb=self._on_progress,
                        status_cb=self._on_transfer_status):
                    ok_count += 1
            self.after(0, lambda: self._on_upload_done(ok_count, total_files))

        threading.Thread(target=_do, daemon=True).start()

    def _on_upload_done(self, ok_count: int, total: int):
        self._hide_progress()
        if ok_count == total:
            self._status_label.configure(
                text=t("s3_uploaded_n").format(count=ok_count))
        else:
            self._status_label.configure(
                text=t("s3_upload_partial").format(ok=ok_count, total=total))
        self._refresh()

    # -- server switch ----------------------------------------------------

    def set_server(self, alias: str | None):
        """Called when user selects a server in sidebar."""
        if alias == self._current_alias:
            return
        self._current_alias = alias
        if not alias:
            self._client = None
            self._tree.delete(*self._tree.get_children())
            self._status_label.configure(text="")
            return
        self._client = None
        self._current_prefix = ""
        self._nav_stack.clear()
        self._tree.delete(*self._tree.get_children())
        self._status_label.configure(text=t("s3_connecting"))

        server = self.store.get_server(alias)
        if not server:
            return

        self._current_bucket = server.get("bucket", "")

        def _connect():
            client = S3Client(server)
            ok = client.connect()
            if ok:
                self._client = client
                self.after(0, self._load_buckets)
            else:
                self.after(0, lambda: self._status_label.configure(
                    text=t("s3_connect_failed")))

        threading.Thread(target=_connect, daemon=True).start()

    def _load_buckets(self):
        if not self._client:
            return

        def _fetch():
            buckets = self._client.list_buckets()
            names = [b["Name"] for b in buckets]
            self.after(0, lambda: self._update_buckets(names))

        threading.Thread(target=_fetch, daemon=True).start()

    def _update_buckets(self, names: list[str]):
        if not names:
            names = [""]
        self._bucket_menu.configure(values=names)
        if self._current_bucket and self._current_bucket in names:
            self._bucket_var.set(self._current_bucket)
        elif names:
            self._bucket_var.set(names[0])
            self._current_bucket = names[0]
        self._refresh()

    def _on_bucket_change(self, value: str):
        self._current_bucket = value
        self._current_prefix = ""
        self._nav_stack.clear()
        self._refresh()

    # -- navigation -------------------------------------------------------

    def _refresh(self):
        if not self._client or not self._current_bucket:
            return
        self._status_label.configure(text=t("s3_loading"))
        self._path_label.configure(text=f"/{self._current_prefix}" if self._current_prefix else "/")

        def _fetch():
            objects, prefixes = self._client.list_objects(
                self._current_bucket, self._current_prefix)
            self.after(0, lambda: self._display(objects, prefixes))

        threading.Thread(target=_fetch, daemon=True).start()

    def _display(self, objects: list[dict], prefixes: list[str]):
        self._tree.delete(*self._tree.get_children())

        # Folders first
        for prefix in sorted(prefixes):
            display_name = prefix[len(self._current_prefix):]
            if display_name.endswith("/"):
                display_name = display_name[:-1]
            self._tree.insert("", "end", values=(
                f"\U0001f4c1 {display_name}/", "", ""),
                tags=("folder",),
            )

        # Files
        for obj in sorted(objects, key=lambda o: o["Key"]):
            name = obj["Key"][len(self._current_prefix):]
            size = _human_size(obj.get("Size", 0))
            modified = ""
            if obj.get("LastModified"):
                modified = obj["LastModified"].strftime("%Y-%m-%d %H:%M:%S")
            self._tree.insert("", "end", values=(name, size, modified),
                              tags=("file",))

        count = len(objects) + len(prefixes)
        self._status_label.configure(text=t("s3_items_count").format(count=count))
        self._back_btn.configure(
            state="normal" if self._current_prefix else "disabled")

        # Show drop hint if empty
        if count == 0:
            self._drop_hint.place(relx=0.5, rely=0.5, anchor="center")
        else:
            self._drop_hint.place_forget()

    def _on_double_click(self, event):
        sel = self._tree.selection()
        if not sel:
            return
        item = self._tree.item(sel[0])
        name = item["values"][0] if item["values"] else ""
        if not isinstance(name, str):
            name = str(name)
        # Check if it's a folder
        if name.endswith("/"):
            # Strip folder icon
            clean = name.replace("\U0001f4c1 ", "").strip()
            self._nav_stack.append(self._current_prefix)
            self._current_prefix = self._current_prefix + clean
            if not self._current_prefix.endswith("/"):
                self._current_prefix += "/"
            self._refresh()
        else:
            # Double-click file = download
            self._download()

    def _go_back(self):
        if self._nav_stack:
            self._current_prefix = self._nav_stack.pop()
        else:
            self._current_prefix = ""
        self._refresh()

    # -- actions ----------------------------------------------------------

    def _upload(self):
        if not self._client or not self._current_bucket:
            return
        paths = filedialog.askopenfilenames()
        if not paths:
            return
        self._upload_files(list(paths))

    def _download(self):
        sel = self._tree.selection()
        if not sel:
            return
        item = self._tree.item(sel[0])
        name = item["values"][0] if item["values"] else ""
        if not isinstance(name, str):
            name = str(name)
        if name.endswith("/"):
            return  # Can't download a folder

        key = self._current_prefix + name
        save_path = filedialog.asksaveasfilename(initialfile=name)
        if not save_path:
            return

        # Get file size for progress
        total_bytes = self._client.get_object_size(self._current_bucket, key)
        label = t("s3_downloading")
        self._status_label.configure(text=label)
        self._show_progress(label, total_bytes)

        def _do():
            ok = self._client.download_file(
                self._current_bucket, key, save_path,
                progress_cb=self._on_progress,
                status_cb=self._on_transfer_status)
            if ok:
                self.after(0, lambda: self._on_download_done(True))
            else:
                self.after(0, lambda: self._on_download_done(False))

        threading.Thread(target=_do, daemon=True).start()

    def _on_download_done(self, success: bool):
        self._hide_progress()
        if success:
            self._status_label.configure(text=t("s3_download_ok"))
        else:
            self._status_label.configure(text=t("s3_download_failed"))

    def _delete(self):
        sel = self._tree.selection()
        if not sel:
            return
        item = self._tree.item(sel[0])
        name = item["values"][0] if item["values"] else ""
        if not isinstance(name, str):
            name = str(name)
        if name.endswith("/"):
            return  # Don't delete prefixes

        key = self._current_prefix + name

        def _do():
            ok = self._client.delete_object(self._current_bucket, key)
            if ok:
                self.after(0, self._refresh)
            else:
                self.after(0, lambda: self._status_label.configure(
                    text=t("s3_delete_failed")))

        self._status_label.configure(text=t("s3_deleting"))
        threading.Thread(target=_do, daemon=True).start()