"""Preview pane: shows the content of the currently selected file.
SaraTag tags live in their own panel now (Tags.py), not here."""

from pathlib import Path
from typing import Optional

import flet as ft

from Core import AppConfig, Palette
from Thumbnails import GetThumbnail, IsThumbnailable

TextExtensions = {
    ".txt", ".md", ".py", ".json", ".toml", ".yaml", ".yml", ".js", ".ts",
    ".css", ".html", ".htm", ".csv", ".log", ".sh", ".fish", ".cfg", ".ini",
    ".scad", ".xml", ".ipynb",
}
TextPreviewCharLimit = 4000


def HumanSize(NumBytes: int) -> str:
    Size = float(NumBytes)
    for Unit in ("B", "KB", "MB", "GB"):
        if Size < 1024 or Unit == "GB":
            return f"{Size:.0f} {Unit}" if Unit == "B" else f"{Size:.1f} {Unit}"
        Size /= 1024
    return f"{Size:.1f} TB"


class Preview(ft.Container):
    def __init__(self, Config: AppConfig, Side: str = "right"):
        self.Config = Config
        self.Body = ft.Column(
            expand=True,
            alignment=ft.MainAxisAlignment.CENTER,
            horizontal_alignment=ft.CrossAxisAlignment.CENTER,
        )
        BorderSide = ft.BorderSide(1, Palette.Surface1)
        Border = ft.Border(right=BorderSide) if Side == "left" else ft.Border(left=BorderSide)

        self.Body.controls = self._BuildContent(None)

        super().__init__(
            content=self.Body,
            width=Config.PreviewWidth,
            padding=16,
            bgcolor=Palette.Mantle,
            border=Border,
        )

    def ShowPath(self, EntryPath: Optional[Path]) -> None:
        self.Body.controls = self._BuildContent(EntryPath)
        self.update()

    def _BuildContent(self, EntryPath: Optional[Path]) -> list[ft.Control]:
        if EntryPath is None:
            return [ft.Text("Nothing selected.", color=Palette.Overlay0)]

        if not EntryPath.exists():
            return [ft.Text("This no longer exists.", color=Palette.Overlay0)]

        if EntryPath.is_dir():
            return [
                ft.Icon(ft.Icons.FOLDER, size=48, color=Palette.Mauve),
                ft.Text(EntryPath.name, weight=ft.FontWeight.BOLD, text_align=ft.TextAlign.CENTER),
                ft.Text("Directory", color=Palette.Overlay0),
            ]

        if IsThumbnailable(EntryPath):
            ThumbnailPath = GetThumbnail(EntryPath, Size=(512, 512))
            if ThumbnailPath is not None:
                return [
                    ft.Image(src=str(ThumbnailPath), fit=ft.BoxFit.CONTAIN, expand=True),
                    ft.Text(EntryPath.name, text_align=ft.TextAlign.CENTER),
                ]

        if EntryPath.suffix.lower() in TextExtensions:
            try:
                Content = EntryPath.read_text(errors="replace")[:TextPreviewCharLimit]
            except OSError:
                Content = None
            if Content is not None:
                return [
                    ft.Text(EntryPath.name, weight=ft.FontWeight.BOLD),
                    ft.Container(
                        content=ft.Text(Content, selectable=True, size=12),
                        expand=True,
                        alignment=ft.Alignment.TOP_LEFT,
                    ),
                ]

        Stat = EntryPath.stat()
        return [
            ft.Icon(ft.Icons.INSERT_DRIVE_FILE_OUTLINED, size=48, color=Palette.Overlay0),
            ft.Text(EntryPath.name, weight=ft.FontWeight.BOLD, text_align=ft.TextAlign.CENTER),
            ft.Text(HumanSize(Stat.st_size), color=Palette.Overlay0),
        ]