// agents/api.rs — Direct API backend for agent execution
//
// Uses poc-agent's OpenAI-compatible API client to call models directly
// (vllm, llama.cpp, OpenRouter, etc.) instead of shelling out to claude CLI.
// Implements the tool loop: send prompt → if tool_calls, execute them →
// send results back → repeat until text response.
//
// Activated when config has api_base_url set.

use crate::agent::api::ApiClient;
use crate::agent::types::*;
use crate::thought::{self, ProcessTracker};
use crate::agent::ui_channel::StreamTarget;

use std::sync::OnceLock;

static API_CLIENT: OnceLock<ApiClient> = OnceLock::new();

fn get_client() -> Result<&'static ApiClient, String> {
    Ok(API_CLIENT.get_or_init(|| {
        let config = crate::config::get();
        let base_url = config.api_base_url.as_deref().unwrap_or("");
        let api_key = config.api_key.as_deref().unwrap_or("");
        let model = config.api_model.as_deref().unwrap_or("qwen-2.5-27b");
        ApiClient::new(base_url, api_key, model)
    }))
}

/// Run agent prompts through the direct API with tool support.
/// For multi-step agents, each prompt is injected as a new user message
/// after the previous step's tool loop completes. The conversation
/// context carries forward naturally between steps.
/// Returns the final text response after all steps complete.
pub async fn call_api_with_tools(
    _agent: &str,
    prompts: &[String],
    temperature: Option<f32>,
    bail_fn: Option<&(dyn Fn(usize) -> Result<(), String> + Sync)>,
    log: &dyn Fn(&str),
) -> Result<String, String> {
    let client = get_client()?;

    // Set up a UI channel — we drain reasoning tokens into the log
    let (ui_tx, mut ui_rx) = crate::agent::ui_channel::channel();

    // Build tool definitions — all shared tools (memory, files, bash, journal)
    let tool_defs = thought::all_definitions();
    let tracker = ProcessTracker::new();

    // Start with the first prompt as a user message
    let mut messages = vec![Message::user(&prompts[0])];
    let mut next_prompt_idx = 1; // index of next prompt to inject
    let reasoning = crate::config::get().api_reasoning.clone();

    let max_turns = 50 * prompts.len();
    for turn in 0..max_turns {
        log(&format!("\n=== TURN {} ({} messages) ===\n", turn, messages.len()));

        let mut last_err = None;
        let mut msg_opt = None;
        let mut usage_opt = None;
        for attempt in 0..5 {
            match client.chat_completion_stream_temp(
                &messages,
                Some(&tool_defs),
                &ui_tx,
                StreamTarget::Autonomous,
                &reasoning,
                temperature,
            ).await {
                Ok((msg, usage)) => {
                    msg_opt = Some(msg);
                    usage_opt = usage;
                    break;
                }
                Err(e) => {
                    let err_str = e.to_string();
                    let is_transient = err_str.contains("IncompleteMessage")
                        || err_str.contains("connection closed")
                        || err_str.contains("connection reset")
                        || err_str.contains("timed out")
                        || err_str.contains("Connection refused");
                    if is_transient && attempt < 4 {
                        log(&format!("transient error (attempt {}): {}, retrying...",
                            attempt + 1, err_str));
                        tokio::time::sleep(std::time::Duration::from_secs(2 << attempt)).await;
                        last_err = Some(e);
                        continue;
                    }
                    let msg_bytes: usize = messages.iter()
                        .map(|m| m.content_text().len())
                        .sum();
                    return Err(format!(
                        "API error on turn {} (~{}KB payload, {} messages, {} attempts): {}",
                        turn, msg_bytes / 1024, messages.len(), attempt + 1, e));
                }
            }
        }
        let msg = msg_opt.unwrap();
        if let Some(ref e) = last_err {
            log(&format!("succeeded after retry (previous error: {})", e));
        }

        if let Some(u) = &usage_opt {
            log(&format!("tokens: {} prompt + {} completion",
                u.prompt_tokens, u.completion_tokens));
        }

        // Drain reasoning tokens from the UI channel into the log
        {
            let mut reasoning_buf = String::new();
            while let Ok(ui_msg) = ui_rx.try_recv() {
                if let crate::agent::ui_channel::UiMessage::Reasoning(r) = ui_msg {
                    reasoning_buf.push_str(&r);
                }
            }
            if !reasoning_buf.is_empty() {
                log(&format!("<think>\n{}\n</think>", reasoning_buf.trim()));
            }
        }

        let has_content = msg.content.is_some();
        let has_tools = msg.tool_calls.as_ref().is_some_and(|tc| !tc.is_empty());

        if has_tools {
            // Push the assistant message with tool calls.
            // Sanitize arguments: vllm re-parses them as JSON when
            // preprocessing the conversation, so invalid JSON from the
            // model crashes the next request.
            let mut sanitized = msg.clone();
            if let Some(ref mut calls) = sanitized.tool_calls {
                for call in calls {
                    if serde_json::from_str::<serde_json::Value>(&call.function.arguments).is_err() {
                        log(&format!("sanitizing malformed args for {}: {}",
                            call.function.name, &call.function.arguments));
                        call.function.arguments = "{}".to_string();
                    }
                }
            }
            messages.push(sanitized);

            // Execute each tool call
            for call in msg.tool_calls.as_ref().unwrap() {
                log(&format!("\nTOOL CALL: {}({})",
                    call.function.name,
                    &call.function.arguments));

                let args: serde_json::Value = match serde_json::from_str(&call.function.arguments) {
                    Ok(v) => v,
                    Err(_) => {
                        log(&format!("malformed tool call args: {}", &call.function.arguments));
                        messages.push(Message::tool_result(
                            &call.id,
                            "Error: your tool call had malformed JSON arguments. Please retry with valid JSON.",
                        ));
                        continue;
                    }
                };

                let output = match thought::dispatch(&call.function.name, &args, &tracker).await {
                    Some(out) => out,
                    None => thought::ToolOutput::error(format!("Unknown tool: {}", call.function.name)),
                };

                log(&format!("TOOL RESULT ({} chars):\n{}", output.text.len(), output.text));

                messages.push(Message::tool_result(&call.id, &output.text));
            }
            continue;
        }

        // Text-only response — step complete
        let text = msg.content_text().to_string();
        if text.is_empty() && !has_content {
            log("empty response, retrying");
            messages.push(Message::user(
                "[system] Your previous response was empty. Please respond with text or use a tool."
            ));
            continue;
        }

        log(&format!("\n=== RESPONSE ===\n\n{}", text));

        // If there are more prompts, check bail condition and inject the next one
        if next_prompt_idx < prompts.len() {
            // Run bail check before continuing to next step
            if let Some(ref check) = bail_fn {
                check(next_prompt_idx)?;
            }
            messages.push(Message::assistant(&text));
            let next = &prompts[next_prompt_idx];
            next_prompt_idx += 1;
            log(&format!("\n=== STEP {}/{} ===\n", next_prompt_idx, prompts.len()));
            messages.push(Message::user(next));
            continue;
        }

        return Ok(text);
    }

    Err(format!("agent exceeded {} tool turns", max_turns))
}

/// Synchronous wrapper — runs the async function on a dedicated thread
/// with its own tokio runtime. Safe to call from any context.
pub fn call_api_with_tools_sync(
    agent: &str,
    prompts: &[String],
    temperature: Option<f32>,
    bail_fn: Option<&(dyn Fn(usize) -> Result<(), String> + Sync)>,
    log: &(dyn Fn(&str) + Sync),
) -> Result<String, String> {
    std::thread::scope(|s| {
        s.spawn(|| {
            let rt = tokio::runtime::Builder::new_current_thread()
                .enable_all()
                .build()
                .map_err(|e| format!("tokio runtime: {}", e))?;
            let agent_name = format!("agent:{}", agent);
            rt.block_on(
                crate::store::TASK_AGENT.scope(agent_name,
                    call_api_with_tools(agent, prompts, temperature, bail_fn, log))
            )
        }).join().unwrap()
    })
}