// test-client: Test client for the Settled Reach simulation server.
//
// Connects via TCP, receives ObserverSnapshots, optionally sends replay
// inputs, and outputs snapshots as text/JSON. Supports golden file
// comparison for deterministic regression testing.
//
// Exit codes:
//   0 = success
//   1 = golden file mismatch
//   2 = connection/protocol error

use clap::Parser;
use std::io::{BufReader, BufWriter};
use std::net::TcpStream;
use std::path::PathBuf;
use std::process;

use settled_reach_server::bridge::framing::{read_framed, write_framed};
use settled_reach_server::bridge::text_renderer::format_snapshot_text;
use settled_reach_server::bridge::types::ObserverSnapshot;

mod golden;
mod replay;

#[derive(Parser)]
#[command(
    name = "test-client",
    about = "Test client for the Settled Reach simulation server"
)]
struct Cli {
    /// Server address (host:port)
    #[arg(long, default_value = "127.0.0.1:9876")]
    connect: String,

    /// JSONL replay file (one JSON array of PlayerInput per tick)
    #[arg(long)]
    replay: Option<PathBuf>,

    /// Output format: structured text to stdout (default)
    #[arg(long)]
    text: bool,

    /// Output format: JSON snapshots to stdout
    #[arg(long)]
    json: bool,

    /// No output (CI assertions only)
    #[arg(long)]
    quiet: bool,

    /// Compare final snapshot against golden JSON file, exit 1 on diff
    #[arg(long)]
    golden: Option<PathBuf>,

    /// Disconnect after N ticks
    #[arg(long)]
    ticks: Option<u64>,
}

enum OutputMode {
    Text,
    Json,
    Quiet,
}

fn main() {
    let cli = Cli::parse();

    let output_mode = if cli.quiet {
        OutputMode::Quiet
    } else if cli.json {
        OutputMode::Json
    } else {
        OutputMode::Text
    };

    // Connect to server
    let stream = match TcpStream::connect(&cli.connect) {
        Ok(s) => s,
        Err(e) => {
            eprintln!("Connection error: {} (address: {})", e, cli.connect);
            process::exit(2);
        }
    };

    let mut reader = BufReader::new(stream.try_clone().unwrap_or_else(|e| {
        eprintln!("Failed to clone TCP stream: {}", e);
        process::exit(2);
    }));
    let mut writer = BufWriter::new(stream);

    // Load replay inputs if provided
    let replay_inputs = cli.replay.as_ref().map(|path| {
        replay::load_replay(path).unwrap_or_else(|e| {
            eprintln!("Replay load error: {}", e);
            process::exit(2);
        })
    });

    let mut tick_count: u64 = 0;
    let mut last_snapshot: Option<ObserverSnapshot> = None;

    loop {
        // Receive snapshot (blocking read)
        let payload = match read_framed(&mut reader) {
            Ok(Some(data)) => data,
            Ok(None) => {
                // Server closed connection — normal shutdown
                break;
            }
            Err(e) => {
                eprintln!("Read error: {}", e);
                process::exit(2);
            }
        };

        let snapshot: ObserverSnapshot = match rmp_serde::from_slice(&payload) {
            Ok(s) => s,
            Err(e) => {
                eprintln!("Deserialization error: {}", e);
                process::exit(2);
            }
        };

        tick_count += 1;

        // Output snapshot
        match output_mode {
            OutputMode::Text => {
                print!("{}", format_snapshot_text(&snapshot));
            }
            OutputMode::Json => {
                let json = serde_json::to_string_pretty(&snapshot).unwrap();
                println!("{}", json);
            }
            OutputMode::Quiet => {}
        }

        last_snapshot = Some(snapshot);

        // Check tick limit before sending next input
        if let Some(max_ticks) = cli.ticks {
            if tick_count >= max_ticks {
                break;
            }
        }

        // Send inputs for next tick
        let inputs = replay_inputs
            .as_ref()
            .and_then(|r| r.get(tick_count as usize - 1))
            .cloned()
            .unwrap_or_default();

        let input_payload = rmp_serde::to_vec(&inputs).unwrap_or_else(|e| {
            eprintln!("Input serialization error: {}", e);
            process::exit(2);
        });
        if let Err(e) = write_framed(&mut writer, &input_payload) {
            eprintln!("Write error: {}", e);
            process::exit(2);
        }
    }

    // Golden file comparison
    if let Some(golden_path) = &cli.golden {
        let snapshot = match last_snapshot {
            Some(s) => s,
            None => {
                eprintln!("No snapshot received for golden comparison");
                process::exit(2);
            }
        };

        let diffs = golden::compare_golden(golden_path, &snapshot).unwrap_or_else(|e| {
            eprintln!("Golden file error: {}", e);
            process::exit(2);
        });

        if !diffs.is_empty() {
            eprintln!("GOLDEN FILE MISMATCH: {}", golden_path.display());
            for diff in &diffs {
                eprintln!("  {}", diff);
            }
            process::exit(1);
        }
    }
}