// JSONL replay file loader for test-client.
// Each line is a JSON array of PlayerInput for one tick.
// Empty array = idle tick (no input sent).

use settled_reach_server::bridge::types::PlayerInput;
use std::path::Path;

/// Load a JSONL replay file. Returns one Vec<PlayerInput> per tick.
///
/// Format: one JSON array per line. Each array contains PlayerInput objects
/// for that tick. Blank lines are skipped. Returns Err with line number on
/// parse failure.
pub fn load_replay(path: &Path) -> Result<Vec<Vec<PlayerInput>>, String> {
    let content = std::fs::read_to_string(path)
        .map_err(|e| format!("failed to read replay file {}: {}", path.display(), e))?;

    let mut ticks = Vec::new();
    for (i, line) in content.lines().enumerate() {
        let line = line.trim();
        if line.is_empty() {
            continue;
        }
        let inputs: Vec<PlayerInput> =
            serde_json::from_str(line).map_err(|e| format!("replay line {}: {}", i + 1, e))?;
        ticks.push(inputs);
    }
    Ok(ticks)
}

#[cfg(test)]
mod tests {
    use super::*;
    use settled_reach_server::bridge::types::PlayerAction;
    use std::io::Write;

    fn write_temp_file(content: &str) -> tempfile::NamedTempFile {
        let mut f = tempfile::NamedTempFile::new().unwrap();
        f.write_all(content.as_bytes()).unwrap();
        f.flush().unwrap();
        f
    }

    #[test]
    fn load_single_tick_single_action() {
        let f = write_temp_file(r#"[{"tick":0,"action":"MoveNorth"}]"#);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 1);
        assert_eq!(ticks[0].len(), 1);
        assert!(ticks[0][0].action.is_movement());
    }

    #[test]
    fn load_multiple_ticks() {
        let content = r#"[{"tick":0,"action":"MoveNorth"}]
[{"tick":1,"action":"MoveEast"}]
[{"tick":2,"action":"MoveSouth"}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 3);
    }

    #[test]
    fn load_multiple_actions_per_tick() {
        let content = r#"[{"tick":0,"action":"MoveNorth"},{"tick":0,"action":"Pause"}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 1);
        assert_eq!(ticks[0].len(), 2);
    }

    #[test]
    fn load_empty_array_idle_tick() {
        let content = "[]";
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 1);
        assert!(ticks[0].is_empty());
    }

    #[test]
    fn blank_lines_skipped() {
        let content = r#"[{"tick":0,"action":"MoveNorth"}]

[{"tick":2,"action":"MoveSouth"}]

"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 2, "blank lines should be skipped, not counted as ticks");
    }

    #[test]
    fn empty_file_returns_empty_vec() {
        let f = write_temp_file("");
        let ticks = load_replay(f.path()).unwrap();
        assert!(ticks.is_empty());
    }

    #[test]
    fn whitespace_only_file_returns_empty_vec() {
        let f = write_temp_file("   \n  \n\n   ");
        let ticks = load_replay(f.path()).unwrap();
        assert!(ticks.is_empty());
    }

    #[test]
    fn invalid_json_reports_line_number() {
        let content = r#"[{"tick":0,"action":"MoveNorth"}]
not valid json
[{"tick":2,"action":"MoveSouth"}]"#;
        let f = write_temp_file(content);
        let err = load_replay(f.path()).unwrap_err();
        assert!(err.contains("replay line 2"), "error should reference line 2, got: {}", err);
    }

    #[test]
    fn missing_file_returns_error() {
        let err = load_replay(Path::new("/nonexistent/replay.jsonl")).unwrap_err();
        assert!(err.contains("failed to read replay file"), "got: {}", err);
    }

    #[test]
    fn interact_action_parses() {
        let content =
            r#"[{"tick":0,"action":{"Interact":{"target_entity_id":42,"verb":"Talk"}}}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 1);
        match &ticks[0][0].action {
            PlayerAction::Interact {
                target_entity_id,
                verb,
            } => {
                assert_eq!(*target_entity_id, Some(42));
                assert_eq!(verb.as_deref(), Some("Talk"));
            }
            other => panic!("expected Interact, got {:?}", other),
        }
    }

    #[test]
    fn teleport_to_hub_parses() {
        let content = r#"[{"tick":0,"action":"TeleportToHub"}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 1);
        assert!(matches!(ticks[0][0].action, PlayerAction::TeleportToHub));
    }

    #[test]
    fn walk_away_parses() {
        let content = r#"[{"tick":0,"action":"WalkAway"}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert!(matches!(ticks[0][0].action, PlayerAction::WalkAway));
    }

    #[test]
    fn mixed_replay_scenario() {
        // Simulates a realistic Gauntlet replay: move, idle, interact, move, teleport
        let content = r#"[{"tick":0,"action":"MoveNorth"}]
[{"tick":1,"action":"MoveNorth"}]
[]
[{"tick":3,"action":{"Interact":{"target_entity_id":100,"verb":"Talk"}}}]
[{"tick":4,"action":"MoveEast"}]
[{"tick":5,"action":"TeleportToHub"}]"#;
        let f = write_temp_file(content);
        let ticks = load_replay(f.path()).unwrap();
        assert_eq!(ticks.len(), 6);
        assert_eq!(ticks[0].len(), 1); // MoveNorth
        assert_eq!(ticks[1].len(), 1); // MoveNorth
        assert_eq!(ticks[2].len(), 0); // Idle
        assert_eq!(ticks[3].len(), 1); // Interact
        assert_eq!(ticks[4].len(), 1); // MoveEast
        assert_eq!(ticks[5].len(), 1); // TeleportToHub
    }
}