"""Themes de l'application : palette d'interface (QSS) + palette du terminal.

Trois themes sont fournis (clair par defaut, bleu nuit, noir). Ils partagent le meme
gabarit `resources/theme.qss`, dont les $variables sont remplacees par la palette
choisie : une seule feuille de style a maintenir au lieu de trois quasi identiques.
"""
from __future__ import annotations

import json
from pathlib import Path
from string import Template

from PySide6.QtCore import Qt
from PySide6.QtGui import QIcon, QPixmap, QPainter, QColor, QFont, QLinearGradient
from PySide6.QtWidgets import QApplication

from app.paths import RESOURCES_DIR, DATA_DIR  # noqa: E402  (chemins valables aussi en .exe)
STYLESHEET_PATH = RESOURCES_DIR / "theme.qss"
SETTINGS_FILE = DATA_DIR / "settings.json"

THEME_LIGHT = "light"
THEME_MIDNIGHT = "midnight"
THEME_BLACK = "black"
DEFAULT_THEME = THEME_LIGHT

# ---------------------------------------------------------------------------
# Palettes d'interface
# ---------------------------------------------------------------------------
UI_PALETTES: dict[str, dict[str, str]] = {
    THEME_LIGHT: {
        "window": "#f4f6f9", "base": "#ffffff", "panel": "#eef1f6", "elevated": "#e4e9f0",
        "input": "#ffffff", "hover": "#dfe6f2", "pressed": "#d2dae8",
        "border": "#d3dae4", "border_strong": "#b9c3d1",
        "text": "#1c2430", "text_dim": "#5c6875", "text_disabled": "#a3adba",
        "accent": "#2f6fed", "accent_hover": "#1f5ed6", "on_accent": "#ffffff",
        "scroll": "#c3ccd9", "scroll_hover": "#a7b3c4",
    },
    THEME_MIDNIGHT: {
        "window": "#0a1220", "base": "#0c1526", "panel": "#0e1a30", "elevated": "#1c2c47",
        "input": "#101c30", "hover": "#172542", "pressed": "#16233b",
        "border": "#1c2c47", "border_strong": "#2a3c5c",
        "text": "#e6ecf6", "text_dim": "#93a4c2", "text_disabled": "#55627c",
        "accent": "#2f6fed", "accent_hover": "#4f8cff", "on_accent": "#ffffff",
        "scroll": "#2a3c5c", "scroll_hover": "#3a527d",
    },
    THEME_BLACK: {
        "window": "#000000", "base": "#0a0a0a", "panel": "#141414", "elevated": "#1f1f1f",
        "input": "#141414", "hover": "#262626", "pressed": "#0f0f0f",
        "border": "#2b2b2b", "border_strong": "#3d3d3d",
        "text": "#e8e8e8", "text_dim": "#9a9a9a", "text_disabled": "#5a5a5a",
        "accent": "#4a9eff", "accent_hover": "#6fb3ff", "on_accent": "#000000",
        "scroll": "#3a3a3a", "scroll_hover": "#525252",
    },
}

# ---------------------------------------------------------------------------
# Palettes du terminal (16 couleurs ANSI + defauts + curseur)
# ---------------------------------------------------------------------------
TERMINAL_PALETTES: dict[str, dict] = {
    THEME_LIGHT: {
        "fg": "#1c2430", "bg": "#ffffff", "cursor": (47, 111, 237, 110),
        "ansi": {
            "black": "#1c2430", "red": "#c0392b", "green": "#2e7d32", "brown": "#a06800",
            "blue": "#1f5ed6", "magenta": "#8e24aa", "cyan": "#00838f", "white": "#5c6875",
            "brightblack": "#8a94a3", "brightred": "#e04b3a", "brightgreen": "#3ca142",
            "brightbrown": "#c98a00", "brightblue": "#2f6fed", "brightmagenta": "#a944c7",
            "brightcyan": "#0aa2b0", "brightwhite": "#1c2430",
        },
    },
    THEME_MIDNIGHT: {
        "fg": "#e6ecf6", "bg": "#0b1220", "cursor": (79, 140, 255, 140),
        "ansi": {
            "black": "#0b1220", "red": "#ff6b81", "green": "#8ce99a", "brown": "#f2c94c",
            "blue": "#4f8cff", "magenta": "#c792ea", "cyan": "#63d4e0", "white": "#dbe4f5",
            "brightblack": "#3a4a68", "brightred": "#ff8a9b", "brightgreen": "#a9e6b5",
            "brightbrown": "#f5d778", "brightblue": "#7aa9ff", "brightmagenta": "#dcb3f0",
            "brightcyan": "#8fe3ec", "brightwhite": "#ffffff",
        },
    },
    THEME_BLACK: {
        "fg": "#e8e8e8", "bg": "#000000", "cursor": (74, 158, 255, 140),
        "ansi": {
            "black": "#000000", "red": "#e05561", "green": "#8cc265", "brown": "#d18f52",
            "blue": "#4aa5f0", "magenta": "#c162de", "cyan": "#42b3c2", "white": "#d0d0d0",
            "brightblack": "#5a5a5a", "brightred": "#ff6b78", "brightgreen": "#a5e075",
            "brightbrown": "#e5a663", "brightblue": "#6fb3ff", "brightmagenta": "#d178ee",
            "brightcyan": "#5fc9d8", "brightwhite": "#ffffff",
        },
    },
}

THEME_LABELS = {
    THEME_LIGHT: "Clair",
    THEME_MIDNIGHT: "Bleu nuit",
    THEME_BLACK: "Noir",
}

_current_theme = DEFAULT_THEME


# ---------------------------------------------------------------------------
# Preference persistante
# ---------------------------------------------------------------------------
def load_saved_theme() -> str:
    try:
        data = json.loads(SETTINGS_FILE.read_text(encoding="utf-8"))
        theme = data.get("theme")
        if theme in UI_PALETTES:
            return theme
    except (OSError, json.JSONDecodeError):
        pass
    return DEFAULT_THEME


def save_theme(theme: str) -> None:
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    data = {}
    try:
        data = json.loads(SETTINGS_FILE.read_text(encoding="utf-8"))
    except (OSError, json.JSONDecodeError):
        pass
    data["theme"] = theme
    try:
        SETTINGS_FILE.write_text(json.dumps(data, indent=2), encoding="utf-8")
    except OSError:
        pass


def current_theme() -> str:
    return _current_theme


def terminal_palette(theme: str | None = None) -> dict:
    return TERMINAL_PALETTES.get(theme or _current_theme, TERMINAL_PALETTES[DEFAULT_THEME])


# ---------------------------------------------------------------------------
# Application du theme
# ---------------------------------------------------------------------------
def apply_theme(app: QApplication, theme: str = DEFAULT_THEME) -> None:
    """Bascule sur le style Fusion (necessaire pour que la QSS s'applique
    uniformement, y compris aux widgets stylises nativement par Windows) puis
    construit la feuille de style a partir de la palette demandee."""
    global _current_theme
    if theme not in UI_PALETTES:
        theme = DEFAULT_THEME
    _current_theme = theme

    app.setStyle("Fusion")
    try:
        template = Template(STYLESHEET_PATH.read_text(encoding="utf-8"))
        app.setStyleSheet(template.safe_substitute(UI_PALETTES[theme]))
    except OSError:
        pass


def build_app_icon() -> QIcon:
    """Genere une icone simple (pas de fichier externe requis) : carre + prompt '>_'"""
    size = 64
    pixmap = QPixmap(size, size)
    pixmap.fill(Qt.transparent)

    painter = QPainter(pixmap)
    painter.setRenderHint(QPainter.Antialiasing)

    gradient = QLinearGradient(0, 0, size, size)
    gradient.setColorAt(0, QColor("#182a4a"))
    gradient.setColorAt(1, QColor("#0a1220"))
    painter.setBrush(gradient)
    painter.setPen(QColor("#2a3c5c"))
    painter.drawRoundedRect(2, 2, size - 4, size - 4, 14, 14)

    font = QFont("Consolas")
    font.setBold(True)
    font.setPointSize(24)
    painter.setFont(font)
    painter.setPen(QColor("#4f8cff"))
    painter.drawText(pixmap.rect(), Qt.AlignCenter, ">_")

    painter.end()
    return QIcon(pixmap)