#!/usr/bin/env python3
"""
Generate an MCC EntityPalette C# file from server-generated registries.json.

The registries.json file is generated by running:
    java -DbundlerMainClass=net.minecraft.data.Main -jar server.jar --reports

Usage:
    python3 tools/gen_entity_palette.py <registries.json> <suffix>

Example:
    python3 tools/gen_entity_palette.py /tmp/mc_reports/reports/registries.json 1219
    # Generates EntityPalette1219.cs
"""

import json
import re
import sys
from pathlib import Path

OUTPUT_DIR = (Path(__file__).resolve().parent.parent /
              "MinecraftClient" / "Mapping" / "EntityPalettes")
ENTITY_TYPE_CS = OUTPUT_DIR.parent / "EntityType.cs"


def mc_name_to_csharp(mc_name: str) -> str:
    """Convert minecraft:snake_case to PascalCase C# enum name."""
    name = mc_name.removeprefix("minecraft:")
    return "".join(word.capitalize() for word in name.split("_"))


def load_known_entity_types() -> set[str]:
    known = set()
    if ENTITY_TYPE_CS.exists():
        with open(ENTITY_TYPE_CS) as f:
            for line in f:
                m = re.match(r'\s+(\w+),?\s*$', line)
                if m:
                    known.add(m.group(1))
    return known


def main():
    if len(sys.argv) != 3:
        print(__doc__)
        sys.exit(1)

    registry_path = Path(sys.argv[1])
    class_suffix = sys.argv[2]

    if not registry_path.exists():
        print(f"Error: {registry_path} not found")
        sys.exit(1)

    with open(registry_path) as f:
        data = json.load(f)

    entities_reg = data.get("minecraft:entity_type", {}).get("entries", {})
    mappings = []
    for entity_key, info in entities_reg.items():
        pid = info["protocol_id"]
        cs_name = mc_name_to_csharp(entity_key)
        mappings.append((pid, cs_name))

    mappings.sort(key=lambda x: x[0])
    print(f"Loaded {len(mappings)} entity types from {registry_path}")

    known = load_known_entity_types()
    missing = [cs for _, cs in mappings if known and cs not in known]
    if missing:
        print(f"\nWARNING: {len(missing)} entity types not found in EntityType.cs enum:")
        for cs_name in missing:
            print(f"  {cs_name}")
        print("\nYou need to add these to EntityType.cs before the palette will compile.")
        print("Insert them in alphabetical order within the enum.")

    class_name = f"EntityPalette{class_suffix}"
    output_path = OUTPUT_DIR / f"{class_name}.cs"

    lines = [
        "using System.Collections.Generic;",
        "",
        "namespace MinecraftClient.Mapping.EntityPalettes",
        "{",
        f"    public class {class_name} : EntityPalette",
        "    {",
        "        private static readonly Dictionary<int, EntityType> mappings = new();",
        "",
        f"        static {class_name}()",
        "        {",
    ]
    for pid, cs_name in mappings:
        lines.append(f"            mappings[{pid}] = EntityType.{cs_name};")
    lines += [
        "        }",
        "",
        "        protected override Dictionary<int, EntityType> GetDict()",
        "        {",
        "            return mappings;",
        "        }",
        "    }",
        "}",
        "",
    ]

    output_path.write_text("\n".join(lines))
    print(f"Generated {output_path} with {len(mappings)} entity types")


if __name__ == "__main__":
    main()