// LLM utilities: model invocation and response parsing
//
// Calls claude CLI as a subprocess. Uses prctl(PR_SET_PDEATHSIG)
// so child processes die when the daemon exits, preventing orphans.

use crate::store::Store;

use regex::Regex;
use std::fs;
use std::os::unix::process::CommandExt;
use std::process::Command;

fn log_usage(agent: &str, model: &str, prompt: &str, response: &str,
             duration_ms: u128, ok: bool) {
    let dir = crate::config::get().data_dir.join("llm-logs").join(agent);
    let _ = fs::create_dir_all(&dir);

    let date = chrono::Local::now().format("%Y-%m-%d");
    let path = dir.join(format!("{}.md", date));

    let ts = chrono::Local::now().format("%H:%M:%S");
    let status = if ok { "ok" } else { "ERROR" };

    let entry = format!(
        "\n## {} — {} ({}, {:.1}s, {})\n\n\
         ### Prompt ({} chars)\n\n\
         ```\n{}\n```\n\n\
         ### Response ({} chars)\n\n\
         ```\n{}\n```\n\n---\n",
        ts, agent, model, duration_ms as f64 / 1000.0, status,
        prompt.len(), prompt,
        response.len(), response,
    );

    use std::io::Write;
    if let Ok(mut f) = fs::OpenOptions::new().create(true).append(true).open(&path) {
        let _ = f.write_all(entry.as_bytes());
    }
}

/// Call a model via claude CLI. Returns the response text.
///
/// Sets PR_SET_PDEATHSIG on the child so it gets SIGTERM if the
/// parent daemon exits — no more orphaned claude processes.
fn call_model(agent: &str, model: &str, prompt: &str) -> Result<String, String> {
    // Write prompt to temp file (claude CLI needs file input for large prompts)
    let tmp = std::env::temp_dir().join(format!("poc-llm-{}-{:?}.txt",
        std::process::id(), std::thread::current().id()));
    fs::write(&tmp, prompt)
        .map_err(|e| format!("write temp prompt: {}", e))?;

    let mut cmd = Command::new("claude");
    cmd.args(["-p", "--model", model, "--tools", "", "--no-session-persistence"])
        .stdin(fs::File::open(&tmp).map_err(|e| format!("open temp: {}", e))?)
        .env_remove("CLAUDECODE");

    // Use separate OAuth credentials for agent work if configured
    if let Some(ref dir) = crate::config::get().agent_config_dir {
        cmd.env("CLAUDE_CONFIG_DIR", dir);
    }

    // Tell hooks this is a daemon agent call, not interactive
    cmd.env("POC_AGENT", "1");

    let start = std::time::Instant::now();

    let result = unsafe {
        cmd.pre_exec(|| {
                libc::prctl(libc::PR_SET_PDEATHSIG, libc::SIGTERM);
                Ok(())
            })
            .output()
    };

    fs::remove_file(&tmp).ok();

    match result {
        Ok(output) => {
            let elapsed = start.elapsed().as_millis();
            if output.status.success() {
                let response = String::from_utf8_lossy(&output.stdout).trim().to_string();
                log_usage(agent, model, prompt, &response, elapsed, true);
                Ok(response)
            } else {
                let stderr = String::from_utf8_lossy(&output.stderr);
                let preview = crate::util::first_n_chars(&stderr, 500);
                log_usage(agent, model, prompt, &preview, elapsed, false);
                Err(format!("claude exited {}: {}", output.status, preview.trim()))
            }
        }
        Err(e) => Err(format!("spawn claude: {}", e)),
    }
}

/// Call Sonnet via claude CLI.
pub(crate) fn call_sonnet(agent: &str, prompt: &str) -> Result<String, String> {
    call_model(agent, "sonnet", prompt)
}

/// Call Haiku via claude CLI (cheaper, faster — good for high-volume extraction).
pub(crate) fn call_haiku(agent: &str, prompt: &str) -> Result<String, String> {
    call_model(agent, "haiku", prompt)
}

/// Parse a JSON response, handling markdown fences.
pub(crate) fn parse_json_response(response: &str) -> Result<serde_json::Value, String> {
    let cleaned = response.trim();
    let cleaned = cleaned.strip_prefix("```json").unwrap_or(cleaned);
    let cleaned = cleaned.strip_prefix("```").unwrap_or(cleaned);
    let cleaned = cleaned.strip_suffix("```").unwrap_or(cleaned);
    let cleaned = cleaned.trim();

    if let Ok(v) = serde_json::from_str(cleaned) {
        return Ok(v);
    }

    // Try to find JSON object or array
    let re_obj = Regex::new(r"\{[\s\S]*\}").unwrap();
    let re_arr = Regex::new(r"\[[\s\S]*\]").unwrap();

    if let Some(m) = re_obj.find(cleaned) {
        if let Ok(v) = serde_json::from_str(m.as_str()) {
            return Ok(v);
        }
    }
    if let Some(m) = re_arr.find(cleaned) {
        if let Ok(v) = serde_json::from_str(m.as_str()) {
            return Ok(v);
        }
    }

    let preview = crate::util::first_n_chars(cleaned, 200);
    Err(format!("no valid JSON in response: {preview}..."))
}

/// Get all keys for prompt context.
pub(crate) fn semantic_keys(store: &Store) -> Vec<String> {
    let mut keys: Vec<String> = store.nodes.keys()
        .cloned()
        .collect();
    keys.sort();
    keys.truncate(200);
    keys
}