//! cb-play — play GROUND headless, against bots (CB-WP-0008 T02;
//! precursor of `cb play`).
//!
//! INTENT stage 0 asks for a **CLI player**. Everything else on that list
//! shipped in CB-WP-0001..0006; until this binary existed, the engine was
//! correct, measured and replayable, and nothing could play it.
//!
//! Exit codes: 0 the game finished, 1 it did not. There is no partial
//! success — a session that ends without an outcome is a failure, and
//! saying otherwise is how a stalled game passes for a played one.

mod inspect;
mod table;

use table::Config;

const USAGE: &str = "\
usage: cb-play [--seed N] [--players N] [--seat N]... [--bot greedy|random]
               [--replay DIR] [--all-bots]

  --seed N       game seed (default 1); the same seed replays identically
  --players N    2..6 seats (default 3)
  --seat N       a seat you play, 0-based, repeatable (default 0)
  --all-bots     no human seats; watch a game play itself
  --bot KIND     policy for every other seat: greedy (default) or random
  --replay DIR   write a .cbreplay bundle of the finished game to DIR
  --record FILE  write the finished game as a scenario YAML
";

fn parse_args(argv: &[String]) -> Result<Config, String> {
    let mut config = Config::default();
    let mut seats: Vec<u8> = Vec::new();
    let mut all_bots = false;
    let mut i = 0;
    let value = |i: usize, argv: &[String], flag: &str| -> Result<String, String> {
        argv.get(i + 1)
            .cloned()
            .ok_or_else(|| format!("{flag} needs a value"))
    };
    while i < argv.len() {
        let flag = argv[i].as_str();
        match flag {
            "--seed" => {
                config.seed = value(i, argv, flag)?
                    .parse()
                    .map_err(|e| format!("--seed: {e}"))?;
                i += 2;
            }
            "--players" => {
                config.players = value(i, argv, flag)?
                    .parse()
                    .map_err(|e| format!("--players: {e}"))?;
                i += 2;
            }
            "--seat" => {
                seats.push(
                    value(i, argv, flag)?
                        .parse()
                        .map_err(|e| format!("--seat: {e}"))?,
                );
                i += 2;
            }
            "--bot" => {
                config.bot = value(i, argv, flag)?;
                i += 2;
            }
            "--record" => {
                config.record = Some(value(i, argv, flag)?.into());
                i += 2;
            }
            "--replay" => {
                config.replay_dir = Some(value(i, argv, flag)?.into());
                i += 2;
            }
            "--all-bots" => {
                all_bots = true;
                i += 1;
            }
            "-h" | "--help" => return Err(USAGE.into()),
            other => return Err(format!("unknown flag {other:?}\n\n{USAGE}")),
        }
    }
    if !(2..=6).contains(&config.players) {
        return Err(format!("GR-O01: {} players is outside 2–6", config.players));
    }
    config.human_seats = if all_bots {
        vec![]
    } else if seats.is_empty() {
        vec![0]
    } else {
        seats
    };
    if let Some(bad) = config.human_seats.iter().find(|s| **s >= config.players) {
        return Err(format!(
            "--seat {bad} is not one of {} seats",
            config.players
        ));
    }
    Ok(config)
}

fn main() {
    let argv: Vec<String> = std::env::args().skip(1).collect();
    let config = match parse_args(&argv) {
        Ok(c) => c,
        Err(message) => {
            eprintln!("{message}");
            std::process::exit(64);
        }
    };

    let stdin = std::io::stdin();
    let stdout = std::io::stdout();
    match table::play(&config, stdin.lock(), stdout.lock()) {
        Ok(summary) => {
            println!(
                "  {} round(s), {} commands, hash {}",
                summary.rounds,
                summary.scenario.commands.len(),
                summary.end_state_hash
            );
            if let Some(path) = summary.bundle {
                println!("  bundle {}", path.display());
            }
            if let Some(path) = summary.recorded {
                println!("  recorded {}", path.display());
            }
        }
        Err(message) => {
            eprintln!("cb-play: {message}");
            std::process::exit(1);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use cb_game_runtime::{run, RunOutcome};
    use games_ground::GroundState;

    fn args(list: &[&str]) -> Vec<String> {
        list.iter().map(|s| s.to_string()).collect()
    }

    /// A scripted transcript plays a full game to `GameEnded`. "0"
    /// always takes the first legal command, which is a real player input
    /// and needs no knowledge of the board.
    ///
    /// Run at **both GR-O01 boundaries and the middle** (T03): the CLI is
    /// where a seat-count assumption would show up as a prompt nobody can
    /// answer.
    #[test]
    fn a_scripted_transcript_plays_a_full_game() {
        for players in [2u8, 3, 6] {
            let config = Config {
                seed: 42,
                players,
                human_seats: vec![0],
                bot: "greedy".into(),
                replay_dir: None,
                record: None,
            };
            let script = "0\n".repeat(400);
            let mut out: Vec<u8> = Vec::new();
            let summary = table::play(&config, script.as_bytes(), &mut out)
                .unwrap_or_else(|e| panic!("{players}p scripted game failed: {e}"));

            assert_eq!(summary.rounds, 5, "{players}p: GR-R09 runs five rounds");
            let text = String::from_utf8(out).expect("utf8");
            assert!(text.contains("OUTCOME"), "{players}p: no outcome reported");
            assert!(text.contains("you are P1"), "{players}p: no prompt");

            // The transcript replays identically — through the scenario
            // runner, not through a second call to the same driver.
            match run::<GroundState>(&summary.scenario) {
                RunOutcome::Passed { .. } => {}
                RunOutcome::Failed { reason, .. } => {
                    panic!("{players}p replay failed: {reason}")
                }
            }
        }
    }

    /// K13 at the boundary that matters: what the human is *shown* must
    /// not contain another seat's face-down selection.
    ///
    /// The human seat is **P3**, deliberately. Seats are asked in order,
    /// so a P1 human is always prompted before anyone has selected and
    /// never sees a hidden selection at all — a test seated there passes
    /// without exercising the rule.
    #[test]
    fn the_prompt_never_shows_a_hidden_selection() {
        let config = Config {
            seed: 42,
            players: 3,
            human_seats: vec![2],
            bot: "greedy".into(),
            replay_dir: None,
            record: None,
        };
        let mut out: Vec<u8> = Vec::new();
        table::play(&config, "0\n".repeat(200).as_bytes(), &mut out).expect("game");
        let text = String::from_utf8(out).expect("utf8");

        // Every rendered Select-step block must show other seats as
        // face-down. A block naming a seat's action before Reveal is a
        // leak; `step Select` and `Shown` never co-occur.
        let mut checked = 0;
        for block in text.split("\nround ") {
            if !block.contains("step Select") {
                continue;
            }
            if let Some(line) = block
                .lines()
                .find(|l| l.trim_start().starts_with("selections:"))
            {
                let others: Vec<&str> = line
                    .split("  ")
                    .filter(|s| s.starts_with("P1") || s.starts_with("P2"))
                    .collect();
                for seat in others {
                    checked += 1;
                    assert!(
                        seat.contains("face-down"),
                        "a Select-step prompt showed {seat:?}: {line}"
                    );
                }
            }
        }
        // The loop above passes trivially if it never found a selections
        // line to check — the harness-does-nothing class, which is why
        // this counts what it inspected.
        assert!(
            checked >= 4,
            "only {checked} other-seat entries inspected across the session"
        );
    }

    /// A session whose input runs out must say so, not finish the game
    /// on the human's behalf.
    #[test]
    fn running_out_of_input_fails_loudly() {
        let config = Config::default();
        let mut out: Vec<u8> = Vec::new();
        let err = table::play(&config, "0\n".as_bytes(), &mut out)
            .expect_err("an exhausted transcript must not finish a game");
        assert!(err.contains("input ended"), "got {err:?}");
    }

    /// `--all-bots` is the flag that makes a game watchable, and the
    /// control that proves the human path is not the only path.
    #[test]
    fn all_bots_needs_no_input_at_all() {
        let config = Config {
            seed: 42,
            players: 3,
            human_seats: vec![],
            bot: "random".into(),
            replay_dir: None,
            record: None,
        };
        let mut out: Vec<u8> = Vec::new();
        let summary = table::play(&config, "".as_bytes(), &mut out).expect("bot game");
        assert_eq!(summary.rounds, 5);
    }

    #[test]
    fn flags_parse_and_bad_ones_are_refused() {
        let c = parse_args(&args(&["--seed", "9", "--players", "4", "--seat", "2"])).unwrap();
        assert_eq!((c.seed, c.players, c.human_seats.clone()), (9, 4, vec![2]));
        assert_eq!(parse_args(&args(&[])).unwrap().human_seats, vec![0]);
        assert!(parse_args(&args(&["--all-bots"]))
            .unwrap()
            .human_seats
            .is_empty());
        // GR-O01's range, refused at the door rather than at setup.
        assert!(parse_args(&args(&["--players", "7"])).is_err());
        assert!(parse_args(&args(&["--players", "1"])).is_err());
        // A seat nobody occupies would silently never be prompted.
        assert!(parse_args(&args(&["--players", "3", "--seat", "3"])).is_err());
        assert!(parse_args(&args(&["--seed"])).is_err());
        assert!(parse_args(&args(&["--nope"])).is_err());
    }

    /// A bundle is written only when asked, and it replays.
    #[test]
    fn a_bundle_is_written_and_replays() {
        let dir = std::env::temp_dir().join(format!("cb-play-{}", std::process::id()));
        let _ = std::fs::remove_dir_all(&dir);
        std::fs::create_dir_all(&dir).expect("tmp");
        let config = Config {
            seed: 42,
            players: 3,
            human_seats: vec![],
            bot: "greedy".into(),
            replay_dir: Some(dir.clone()),
            record: Some(dir.join("session.yaml")),
        };
        let mut out: Vec<u8> = Vec::new();
        let summary = table::play(&config, "".as_bytes(), &mut out).expect("game");
        let bundle = summary.bundle.expect("bundle path");
        assert!(bundle.join("manifest.yaml").exists());
        assert!(bundle.join("commands.log").exists());
        let report = cb_game_runtime::replay::replay::<GroundState>(&bundle)
            .unwrap_or_else(|e| panic!("bundle does not replay: {e}"));
        assert_eq!(report.hash, summary.end_state_hash);

        // The recorded scenario is a file the runner can execute, which
        // is what makes a played session a regression test.
        let text = std::fs::read_to_string(summary.recorded.expect("record path")).expect("read");
        let parsed = cb_game_runtime::ScenarioFile::from_yaml(&text).expect("parse");
        assert!(matches!(
            run::<GroundState>(&parsed),
            RunOutcome::Passed { .. }
        ));
        let _ = std::fs::remove_dir_all(&dir);
    }
}