#!/usr/bin/env python3
"""Generate crates/horizon-protocol/src/ids.rs from the vanilla data generator's
packets report (`java -DbundlerMainClass=net.minecraft.data.Main -jar server.jar --reports`).

Packet ids are protocol facts (the order packets are registered in each
connection state); the report is the authoritative source for them.
"""

import argparse
import json
from pathlib import Path

try:
    from . import lab
except ImportError:
    import lab

ROOT = Path(__file__).resolve().parents[1]
STATES = ["handshake", "status", "login", "configuration", "play"]
DIRECTIONS = ["clientbound", "serverbound"]


def const_name(name):
    return name.split(":", 1)[1].replace("/", "_").upper()


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--report", type=Path, default=ROOT / ".local/datagen/out/reports/packets.json")
    parser.add_argument("--out", type=Path, default=ROOT / "crates/horizon-protocol/src/ids.rs")
    args = parser.parse_args()
    report = json.loads(args.report.read_text())
    info = lab.version_info()
    lines = [
        f"//! Packet ids per connection state and direction for protocol {info['protocol_version']} ({info['name']}).",
        "//! Generated by tools/generate_packet_ids.py from the data generator's",
        "//! packets report; do not edit by hand.",
        "#![allow(missing_docs)]",
        "use crate::{Direction, State};",
        "",
    ]
    tables = []
    for state in STATES:
        lines.append(f"pub mod {state} {{")
        for direction in DIRECTIONS:
            packets = report.get(state, {}).get(direction, {})
            if not packets:
                continue
            ordered = sorted(packets.items(), key=lambda kv: kv[1]["protocol_id"])
            assert [e["protocol_id"] for _, e in ordered] == list(range(len(ordered))), (state, direction)
            lines.append(f"    pub mod {direction} {{")
            for name, entry in ordered:
                lines.append(f"        pub const {const_name(name)}: i32 = {entry['protocol_id']};")
            lines.append("        /// Packet names indexed by id.")
            names = ", ".join(f'"{name.split(":", 1)[1]}"' for name, _ in ordered)
            lines.append(f"        pub const NAMES: &[&str] = &[{names}];")
            lines.append("    }")
            tables.append((state, direction))
        lines.append("}")
    lines.append("")
    lines.append("/// The packet name for an id, if the state and direction define it.")
    lines.append("pub fn name(state: State, direction: Direction, id: i32) -> Option<&'static str> {")
    lines.append("    let names: &[&str] = match (state, direction) {")
    for state, direction in tables:
        lines.append(
            f"        (State::{state.capitalize()}, Direction::{direction.capitalize()}) => {state}::{direction}::NAMES,"
        )
    lines.append("        _ => &[],")
    lines.append("    };")
    lines.append("    usize::try_from(id).ok().and_then(|i| names.get(i)).copied()")
    lines.append("}")
    args.out.write_text("\n".join(lines) + "\n")


if __name__ == "__main__":
    main()