//! Get completion suggestions from LSP.
//!
//! Sends a `textDocument/completion` request to the connected language
//! server for a given file position.

use crate::tools::{Tool, ToolCtx};
use anyhow::Result;
use serde_json::{json, Value};
use tracing::{info, error, instrument};

/// Tool that requests code completion suggestions from an LSP server.
///
/// Flow: parse language/path/line/character → lock LSP manager → find client
/// → send `textDocument/completion` → return pretty-printed JSON response.
pub struct LspCompletion;

impl Tool for LspCompletion {
    fn name(&self) -> &'static str {
        "lsp_completion"
    }

    fn description(&self) -> &'static str {
        "Get completion suggestions at a position"
    }

    fn parameters(&self) -> Value {
        json!({
            "type": "object",
            "properties": {
                "language": {
                    "type": "string",
                    "description": "Language identifier"
                },
                "path": {
                    "type": "string",
                    "description": "File path"
                },
                "line": {
                    "type": "integer",
                    "description": "Line number (0-based)"
                },
                "character": {
                    "type": "integer",
                    "description": "Character offset (0-based)"
                }
            },
            "required": ["language", "path", "line", "character"]
        })
    }

    #[instrument(skip(self, ctx, args))]
    fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
        let language = crate::tools::arg_str(args, "language")?;
        let path = crate::tools::arg_str(args, "path")?;
        let line = args.get("line").and_then(|v| v.as_i64()).unwrap_or(0);
        let character = args.get("character").and_then(|v| v.as_i64()).unwrap_or(0);

        info!(language, path, line, character, "LSP completion requested");

        let manager = match ctx.lsp_manager.lock() {
            Ok(g) => g,
            Err(poisoned) => {
                error!("LSP manager mutex poisoned, recovering");
                poisoned.into_inner()
            }
        };
        if let Some(client) = manager.get_client(&language) {
            let result = client.send_request("textDocument/completion", &json!({
                "textDocument": { "uri": format!("file://{}", path) },
                "position": { "line": line, "character": character }
            }))?;
            Ok(serde_json::to_string_pretty(&result)?)
        } else {
            anyhow::bail!("no LSP client connected for '{language}'")
        }
    }
}