//! Per-turn claude invocation shared by `hive-ag3nt` and `hive-m1nd`. The
//! two binaries differ only in their MCP `Flavor` (agent surface vs.
//! manager surface) and their wake-prompt wording; the spawn shape,
//! arg-vector, stdin plumbing, and stream-json pumping are identical.

use std::path::{Path, PathBuf};
use std::process::Stdio;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, Mutex};
use std::time::Duration;

use anyhow::{Result, bail};
use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
use tokio::process::Command;

use crate::events::{Bus, LiveEvent};
use crate::login::{self, LoginState};
use crate::mcp;

/// Inline `--settings` JSON applied to every claude invocation. We turn off
/// claude's in-session auto-compaction and its cross-session auto-memory
/// because hyperhive owns those concerns: compaction is operator/harness-
/// driven (`/compact` on overflow), notes persistence is a hyperhive
/// concern (planned, not yet wired). Unknown keys are silently ignored by
/// claude-code; if the key names ever rename, we'll spot it because
/// auto-compact will start firing mid-turn again.
const CLAUDE_SETTINGS: &str = r#"{"autoCompactEnabled":false,"autoMemoryEnabled":false}"#;

/// Regex-ish marker claude-code emits when context overflows. Same string
/// bitburner-agent watches for. Empirically reliable across claude-code
/// versions; if it ever changes, compaction won't fire and we'll see a
/// claude exit with a useful error in the live view.
const PROMPT_TOO_LONG_MARKER: &str = "Prompt is too long";

/// Drop the MCP config blob claude reads from `--mcp-config <path>`.
/// `socket` is the hyperhive per-container socket (forwarded to the child
/// as `--socket <path>`); `binary_subcommand` is e.g. `"mcp"` for sub-agents
/// or `"mcp"` for the manager (both binaries name their MCP subcommand the
/// same — the differentiator is which binary `/proc/self/exe` resolves to).
pub async fn write_mcp_config(socket: &Path) -> Result<PathBuf> {
    let parent = socket.parent().unwrap_or_else(|| Path::new("/run/hive"));
    tokio::fs::create_dir_all(parent).await.ok();
    let path = parent.join("claude-mcp-config.json");
    let exe = std::env::current_exe()
        .ok()
        .map_or_else(|| "hive-ag3nt".into(), |p| p.display().to_string());
    let body = mcp::render_claude_config(&exe, socket);
    tokio::fs::write(&path, body).await?;
    tracing::info!(path = %path.display(), "wrote claude MCP config");
    Ok(path)
}

/// Write the agent's / manager's static system prompt to a file next to
/// the MCP config and return the path. Passed to claude via
/// `--system-prompt-file`, replacing claude's default system prompt with
/// the role + tools instructions. Per-turn prompts become much smaller
/// (just the wake message body).
pub async fn write_system_prompt(
    socket: &Path,
    label: &str,
    flavor: mcp::Flavor,
) -> Result<PathBuf> {
    let parent = socket.parent().unwrap_or_else(|| Path::new("/run/hive"));
    tokio::fs::create_dir_all(parent).await.ok();
    let template = match flavor {
        mcp::Flavor::Agent => include_str!("../prompts/agent.md"),
        mcp::Flavor::Manager => include_str!("../prompts/manager.md"),
    };
    let body = template.replace("{label}", label);
    let path = parent.join("claude-system-prompt.md");
    tokio::fs::write(&path, body).await?;
    tracing::info!(path = %path.display(), "wrote claude system prompt");
    Ok(path)
}

/// One claude turn's outcome. The harness uses this to decide whether to
/// transparently kick off a compaction and retry.
#[derive(Debug)]
pub enum TurnOutcome {
    Ok,
    /// claude saw "Prompt is too long" — the session needs compacting.
    /// Run `compact_session()` then retry the same wake-up prompt.
    PromptTooLong,
    Failed(anyhow::Error),
}

/// Drive one turn end-to-end, transparently compacting + retrying once on
/// `Prompt is too long`. Both the sub-agent and manager loops call this.
pub async fn drive_turn(
    prompt: &str,
    mcp_config: &Path,
    system_prompt: &Path,
    bus: &Bus,
    flavor: mcp::Flavor,
) -> TurnOutcome {
    match run_turn(prompt, mcp_config, system_prompt, bus, flavor).await {
        TurnOutcome::PromptTooLong => {
            if let Err(e) = compact_session(bus).await {
                tracing::warn!(error = %format!("{e:#}"), "compact failed");
                return TurnOutcome::Failed(e);
            }
            run_turn(prompt, mcp_config, system_prompt, bus, flavor).await
        }
        other => other,
    }
}

/// Emit the per-turn `TurnEnd` event + log line. Single owner so the
/// agent and manager loops agree on outcome semantics.
pub fn emit_turn_end(bus: &Bus, outcome: &TurnOutcome) {
    match outcome {
        TurnOutcome::Ok | TurnOutcome::PromptTooLong => {
            bus.emit(LiveEvent::TurnEnd {
                ok: true,
                note: None,
            });
            tracing::info!("turn finished");
        }
        TurnOutcome::Failed(e) => {
            let note = format!("{e:#}");
            bus.emit(LiveEvent::TurnEnd {
                ok: false,
                note: Some(note.clone()),
            });
            tracing::warn!(error = %note, "turn failed");
        }
    }
}

/// Block until the bound `~/.claude/` dir contains a session, polling
/// `claude_dir` on a `poll_ms` interval (min 2s). Flips `state` to
/// `Online` when login lands; caller resumes its serve loop.
pub async fn wait_for_login(claude_dir: &Path, state: Arc<Mutex<LoginState>>, poll_ms: u64) {
    tracing::warn!(
        claude_dir = %claude_dir.display(),
        "no claude session — staying in partial-run mode (web UI only)"
    );
    let probe = Duration::from_millis(poll_ms.max(2000));
    loop {
        tokio::time::sleep(probe).await;
        if login::has_session(claude_dir) {
            tracing::info!("claude session detected — entering turn loop");
            *state.lock().unwrap() = LoginState::Online;
            return;
        }
    }
}

/// Spawn `claude` for one turn and pump `stream-json` stdout into the
/// live event bus. Prompt goes over stdin (variadic
/// `--allowedTools`/`--tools` would otherwise eat a trailing positional
/// prompt). The session is persistent across turns via `--continue` and
/// claude's in-session auto-compact is disabled via `--settings` so it
/// doesn't stall mid-turn — hyperhive owns compaction.
pub async fn run_turn(
    prompt: &str,
    mcp_config: &Path,
    system_prompt: &Path,
    bus: &Bus,
    flavor: mcp::Flavor,
) -> TurnOutcome {
    match run_claude(
        prompt,
        mcp_config,
        Some(system_prompt),
        bus,
        flavor,
        ClaudeMode::Turn,
    )
    .await
    {
        Ok(too_long) if too_long => TurnOutcome::PromptTooLong,
        Ok(_) => TurnOutcome::Ok,
        Err(e) => TurnOutcome::Failed(e),
    }
}

/// Run claude's built-in `/compact` slash command on the persistent
/// session so the next turn can fit. No MCP tools needed; we just feed
/// `/compact` over stdin and let claude rewrite its own history.
pub async fn compact_session(bus: &Bus) -> Result<()> {
    bus.emit(LiveEvent::Note(
        "context overflow — running /compact on the persistent session".into(),
    ));
    let _ = run_claude(
        "/compact",
        Path::new("/dev/null"),
        None,
        bus,
        mcp::Flavor::Agent, // tool surface unused for /compact
        ClaudeMode::Compact,
    )
    .await?;
    bus.emit(LiveEvent::Note("/compact done".into()));
    Ok(())
}

#[derive(Clone, Copy)]
enum ClaudeMode {
    Turn,
    Compact,
}

async fn run_claude(
    prompt: &str,
    mcp_config: &Path,
    system_prompt: Option<&Path>,
    bus: &Bus,
    flavor: mcp::Flavor,
    mode: ClaudeMode,
) -> Result<bool> {
    let mut cmd = Command::new("claude");
    cmd.arg("--print")
        .arg("--verbose")
        .arg("--output-format")
        .arg("stream-json")
        .arg("--model")
        .arg("haiku")
        .arg("--continue")
        .arg("--settings")
        .arg(CLAUDE_SETTINGS);
    if let Some(p) = system_prompt {
        cmd.arg("--system-prompt-file").arg(p);
    }
    if let ClaudeMode::Turn = mode {
        cmd.arg("--mcp-config")
            .arg(mcp_config)
            .arg("--strict-mcp-config")
            .arg("--tools")
            .arg(mcp::builtin_tools_arg())
            .arg("--allowedTools")
            .arg(mcp::allowed_tools_arg(flavor));
    }
    let mut child = cmd
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .spawn()?;

    if let Some(mut stdin) = child.stdin.take() {
        stdin.write_all(prompt.as_bytes()).await?;
        stdin.shutdown().await.ok();
        drop(stdin);
    }
    let stdout = child.stdout.take().expect("piped stdout");
    let stderr = child.stderr.take().expect("piped stderr");

    let prompt_too_long = Arc::new(AtomicBool::new(false));
    let flag_out = prompt_too_long.clone();
    let flag_err = prompt_too_long.clone();
    let bus_out = bus.clone();
    let bus_err = bus.clone();
    let pump_stdout = tokio::spawn(async move {
        let mut reader = BufReader::new(stdout).lines();
        while let Ok(Some(line)) = reader.next_line().await {
            if line.contains(PROMPT_TOO_LONG_MARKER) {
                flag_out.store(true, Ordering::Relaxed);
            }
            match serde_json::from_str::<serde_json::Value>(&line) {
                Ok(v) => bus_out.emit(LiveEvent::Stream(v)),
                Err(_) => bus_out.emit(LiveEvent::Note(format!("(non-json) {line}"))),
            }
        }
    });
    let pump_stderr = tokio::spawn(async move {
        let mut reader = BufReader::new(stderr).lines();
        while let Ok(Some(line)) = reader.next_line().await {
            if line.contains(PROMPT_TOO_LONG_MARKER) {
                flag_err.store(true, Ordering::Relaxed);
            }
            bus_err.emit(LiveEvent::Note(format!("stderr: {line}")));
        }
    });

    let status = child.wait().await?;
    let _ = pump_stdout.await;
    let _ = pump_stderr.await;
    let too_long = prompt_too_long.load(Ordering::Relaxed);
    if !status.success() && !too_long {
        bail!("claude exited {status}");
    }
    Ok(too_long)
}