#!/usr/bin/env python3
"""Generate the Godot in-game Theme (`ui_theme.tres`) from the design-token SoT.

The single source of truth for the Age of Dwarves visual language is
`.project/designs/design-tokens.json` (W3C / style-dictionary format). This
script compiles those tokens into a complete Godot `Theme` resource:

  * StyleBoxFlat sub-resources for panels, buttons (5 states), and list rows,
    with token-driven background / border colors, corner radii (§6) and
    border widths.
  * Default theme colors + font sizes for Button / Label / Panel /
    PanelContainer / ItemList / RichTextLabel (§3 / §4).
  * A `metadata/tokens` JSON blob carrying the entire `color.*` token tree as
    flat dotted keys (e.g. `accent.gold`, `text.primary`, `semantic.positive`).
    `ThemeAssets.color(name)` resolves names against this blob at runtime — the
    accessor is therefore data-driven from the SoT with no hardcoded color map.

`ui_theme.tres` is a GENERATED artifact. Never hand-edit it; edit the tokens
and re-run. The output is deterministic (sorted keys, fixed float formatting,
stable sub-resource ids, preserved uid) so `--check` is a meaningful drift gate
for CI.

Usage:
    tools/build-ui-theme.py            # regenerate ui_theme.tres in place
    tools/build-ui-theme.py --check    # exit 1 if the .tres is stale (no write)
    tools/build-ui-theme.py --print    # write nothing, dump to stdout
"""

from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path

# Repo root = two levels up from tools/build-ui-theme.py
REPO_ROOT = Path(__file__).resolve().parent.parent
TOKENS_PATH = REPO_ROOT / ".project" / "designs" / "design-tokens.json"
OUTPUT_PATH = REPO_ROOT / "public" / "games" / "age-of-dwarves" / "ui_theme.tres"

# Preserve the existing resource uid so path/uid references stay stable.
THEME_UID = "uid://ui_theme_fantasy"


# --------------------------------------------------------------------------- #
# Token access
# --------------------------------------------------------------------------- #
def load_tokens() -> dict:
    with TOKENS_PATH.open(encoding="utf-8") as fh:
        return json.load(fh)


def _walk_colors(node: dict, prefix: str, out: dict[str, str]) -> None:
    """Recursively flatten the `color.*` subtree into dotted -> hex strings.

    A token leaf is a dict carrying a `$value`. Intermediate groups recurse.
    """
    for key, value in node.items():
        if key.startswith("$"):
            continue
        if not isinstance(value, dict):
            continue
        path = f"{prefix}.{key}" if prefix else key
        if "$value" in value:
            out[path] = str(value["$value"]).lstrip("#").lower()
        else:
            _walk_colors(value, path, out)


def flatten_color_tokens(tokens: dict) -> dict[str, str]:
    """All `color.*` tokens as a flat {dotted_name: 'rrggbb[aa]'} dict."""
    out: dict[str, str] = {}
    _walk_colors(tokens.get("color", {}), "", out)
    return dict(sorted(out.items()))


def _px(value) -> float:
    """'14px' / 14 / '14' -> 14.0."""
    s = str(value).strip().lower().removesuffix("px")
    return float(s)


def font_size(tokens: dict, name: str) -> int:
    return int(_px(tokens["typography"]["fontSize"][name]["$value"]))


def radius(tokens: dict, name: str) -> int:
    return int(_px(tokens["borderRadius"][name]["$value"]))


def border_w(tokens: dict, name: str) -> int:
    return int(_px(tokens["borderWidth"][name]["$value"]))


def spacing(tokens: dict, name: str) -> float:
    return _px(tokens["spacing"][name]["$value"])


# --------------------------------------------------------------------------- #
# Hex -> Godot Color
# --------------------------------------------------------------------------- #
def hex_to_color(hex_str: str) -> str:
    """Convert an SoT hex token to a Godot `Color(r, g, b, a)` literal string.

    Godot's `Color.html()` treats 8-digit hex as RRGGBBAA (verified on the
    target runtime), so this generator uses the identical byte order to keep
    the .tres and the runtime `color()` accessor in agreement.
    """
    h = hex_str.lstrip("#").lower()
    if len(h) == 6:
        h += "ff"
    if len(h) != 8:
        raise ValueError(f"unsupported hex token: {hex_str!r}")
    r = int(h[0:2], 16) / 255.0
    g = int(h[2:4], 16) / 255.0
    b = int(h[4:6], 16) / 255.0
    a = int(h[6:8], 16) / 255.0
    return "Color(%s, %s, %s, %s)" % tuple(_fmt_float(v) for v in (r, g, b, a))


def _fmt_float(v: float) -> str:
    """Deterministic float formatting: trim trailing zeros, keep at least 0/1."""
    s = f"{v:.6f}".rstrip("0").rstrip(".")
    return s if s else "0"


def color_of(colors: dict[str, str], dotted: str) -> str:
    return hex_to_color(colors[dotted])


# --------------------------------------------------------------------------- #
# StyleBoxFlat emission
# --------------------------------------------------------------------------- #
def stylebox(
    sub_id: str,
    *,
    bg: str,
    border: str,
    border_width: int,
    corner: int,
    margins: tuple[float, float, float, float] | None = None,
) -> str:
    """Render one [sub_resource type="StyleBoxFlat"] block."""
    lines = [
        f'[sub_resource type="StyleBoxFlat" id="{sub_id}"]',
        f"bg_color = {bg}",
        f"border_width_left = {border_width}",
        f"border_width_top = {border_width}",
        f"border_width_right = {border_width}",
        f"border_width_bottom = {border_width}",
        f"border_color = {border}",
        f"corner_radius_top_left = {corner}",
        f"corner_radius_top_right = {corner}",
        f"corner_radius_bottom_left = {corner}",
        f"corner_radius_bottom_right = {corner}",
    ]
    if margins is not None:
        ml, mt, mr, mb = (_fmt_float(m) for m in margins)
        lines += [
            f"content_margin_left = {ml}",
            f"content_margin_top = {mt}",
            f"content_margin_right = {mr}",
            f"content_margin_bottom = {mb}",
        ]
    return "\n".join(lines)


# --------------------------------------------------------------------------- #
# Theme assembly
# --------------------------------------------------------------------------- #
def build_theme_text(tokens: dict) -> str:
    colors = flatten_color_tokens(tokens)

    r_panel = radius(tokens, "panel")
    r_button = radius(tokens, "button")
    r_list = radius(tokens, "list")
    bw_default = border_w(tokens, "default")
    bw_emphasis = border_w(tokens, "emphasis")

    # Margins from the spacing scale (§5): panels 12/6, buttons 12/6.
    pad_h = spacing(tokens, "3")  # 12px horizontal
    pad_v = spacing(tokens, "2")  # 8px vertical
    btn_h = spacing(tokens, "3")  # 12px
    btn_v = spacing(tokens, "2")  # 8px

    fs_base = font_size(tokens, "base")
    fs_sm = font_size(tokens, "sm")

    c = lambda name: color_of(colors, name)  # noqa: E731

    subs = [
        stylebox(
            "StyleBoxFlat_panel",
            bg=c("background.panel"),
            border=c("border.panel"),
            border_width=bw_default,
            corner=r_panel,
            margins=(pad_h, pad_v, pad_h, pad_v),
        ),
        stylebox(
            "StyleBoxFlat_button_normal",
            bg=c("button.bgNormal"),
            border=c("border.panel"),
            border_width=bw_default,
            corner=r_button,
            margins=(btn_h, btn_v, btn_h, btn_v),
        ),
        stylebox(
            "StyleBoxFlat_button_hover",
            bg=c("button.bgHover"),
            border=c("accent.goldBright"),
            border_width=bw_default,
            corner=r_button,
            margins=(btn_h, btn_v, btn_h, btn_v),
        ),
        stylebox(
            "StyleBoxFlat_button_pressed",
            bg=c("button.bgPressed"),
            border=c("accent.goldPress"),
            border_width=bw_emphasis,
            corner=r_button,
            margins=(btn_h, btn_v, btn_h, btn_v),
        ),
        stylebox(
            "StyleBoxFlat_button_focus",
            bg="Color(0, 0, 0, 0)",
            border=c("border.focus"),
            border_width=bw_emphasis,
            corner=r_button,
        ),
        stylebox(
            "StyleBoxFlat_item_list_bg",
            bg=c("background.list"),
            border=c("border.list"),
            border_width=bw_default,
            corner=r_list,
        ),
        stylebox(
            "StyleBoxFlat_item_list_selected",
            bg=c("background.listSelected"),
            border=c("border.listSelected"),
            border_width=bw_default,
            corner=r_list,
        ),
    ]

    # metadata/tokens — entire color tree, flat dotted keys, sorted, compact.
    tokens_blob = json.dumps(colors, separators=(",", ":"), sort_keys=True)
    tokens_blob_escaped = tokens_blob.replace("\\", "\\\\").replace('"', '\\"')

    resource_lines = [
        "[resource]",
        f'metadata/tokens = "{tokens_blob_escaped}"',
        f"Button/colors/font_color = {c('text.button')}",
        f"Button/colors/font_hover_color = {c('text.buttonHover')}",
        f"Button/colors/font_pressed_color = {c('text.buttonPressed')}",
        f"Button/colors/font_focus_color = {c('text.buttonHover')}",
        f"Button/colors/font_disabled_color = {c('text.disabled')}",
        f"Button/font_sizes/font_size = {fs_base}",
        'Button/styles/normal = SubResource("StyleBoxFlat_button_normal")',
        'Button/styles/hover = SubResource("StyleBoxFlat_button_hover")',
        'Button/styles/pressed = SubResource("StyleBoxFlat_button_pressed")',
        'Button/styles/focus = SubResource("StyleBoxFlat_button_focus")',
        'Button/styles/disabled = SubResource("StyleBoxFlat_button_normal")',
        f"Label/colors/font_color = {c('text.primary')}",
        f"Label/font_sizes/font_size = {fs_base}",
        'PanelContainer/styles/panel = SubResource("StyleBoxFlat_panel")',
        'Panel/styles/panel = SubResource("StyleBoxFlat_panel")',
        f"ItemList/colors/font_color = {c('text.primary')}",
        f"ItemList/colors/font_selected_color = {c('text.buttonHover')}",
        f"ItemList/font_sizes/font_size = {fs_sm}",
        'ItemList/styles/panel = SubResource("StyleBoxFlat_item_list_bg")',
        'ItemList/styles/selected = SubResource("StyleBoxFlat_item_list_selected")',
        'ItemList/styles/selected_focus = SubResource("StyleBoxFlat_item_list_selected")',
        f"RichTextLabel/colors/default_color = {c('text.primary')}",
        f"RichTextLabel/font_sizes/normal_font_size = {fs_sm}",
    ]

    parts = [
        f'[gd_resource type="Theme" format=3 uid="{THEME_UID}"]',
        "",
    ]
    for sub in subs:
        parts.append("")
        parts.append(sub)
    parts.append("")
    parts.append("\n".join(resource_lines))
    return "\n".join(parts).lstrip("\n") + "\n"


# --------------------------------------------------------------------------- #
# CLI
# --------------------------------------------------------------------------- #
def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--check",
        action="store_true",
        help="exit 1 if ui_theme.tres differs from the regenerated output (no write)",
    )
    parser.add_argument(
        "--print",
        dest="print_only",
        action="store_true",
        help="print the generated .tres to stdout, write nothing",
    )
    args = parser.parse_args()

    tokens = load_tokens()
    text = build_theme_text(tokens)

    if args.print_only:
        sys.stdout.write(text)
        return 0

    if args.check:
        current = OUTPUT_PATH.read_text(encoding="utf-8") if OUTPUT_PATH.exists() else ""
        if current == text:
            print(f"OK: {OUTPUT_PATH.relative_to(REPO_ROOT)} is up to date.")
            return 0
        print(
            f"DRIFT: {OUTPUT_PATH.relative_to(REPO_ROOT)} is stale.\n"
            "Run tools/build-ui-theme.py to regenerate it.",
            file=sys.stderr,
        )
        return 1

    OUTPUT_PATH.write_text(text, encoding="utf-8")
    print(f"Wrote {OUTPUT_PATH.relative_to(REPO_ROOT)} ({len(text)} bytes).")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())