//! Tool for reading a single memory entry or listing the whole memory index.

use std::fmt::Write;
use serde_json::{json, Value};
use anyhow::{Result, anyhow};
use super::super::Tool;
use super::super::ToolCtx;
use crate::model::memory::Memory;

/// Tool that reads one memory entry by name, or lists all entries when name is omitted.
pub struct Recall;

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

    fn description(&self) -> &'static str {
        "Read memory entries. Pass a name to read a specific entry, or omit name to list all entries in the memory index. Use this to find stored lessons, references, and project conventions."
    }

    fn parameters(&self) -> Value {
        json!({
            "type": "object",
            "properties": {
                "name": {
                    "type": "string",
                    "description": "Optional: exact name of a specific memory entry to read. If omitted, lists all entries."
                }
            }
        })
    }

    /// Read a specific memory entry, or fall back to listing all entries.
    ///
    /// Flow: if `name` present and non-empty → `Memory::read` and format as frontmatter
    ///       + body; otherwise → `list_all`.
    ///
    /// Return: formatted memory content, or the full index listing.
    fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
        if let Some(name) = args.get("name").and_then(|v| v.as_str()) {
            if name.is_empty() {
                return Ok(list_all(ctx));
            }
            let memory = Memory::read(&ctx.memory_dir, name)
                .map_err(|e| anyhow!("memory '{name}' not found: {e}"))?;
            Ok(format!(
                "---\nname: {}\ndescription: {}\nkind: {}\nlifecycle: {}\n---\n\n{}",
                memory.name,
                memory.description,
                memory.kind,
                memory.lifecycle,
                memory.content,
            ))
        } else {
            Ok(list_all(ctx))
        }
    }
}

/// List every memory entry in `ctx.memory_dir` as a one-line summary index.
///
/// Flow: `Memory::list` names → for each, try `Memory::read` for kind/description →
///       fall back to bare name if the file can't be parsed.
///
/// Return: `Ok` with the formatted index (never fails; missing dir yields "(no memory entries)").
fn list_all(ctx: &ToolCtx) -> String {
    let names = Memory::list(&ctx.memory_dir);
    if names.is_empty() {
        return "(no memory entries)".to_string();
    }
    let mut lines = String::new();
    for name in &names {
        if let Ok(mem) = Memory::read(&ctx.memory_dir, name) {
            let _ = writeln!(lines, "- {} [{}]: {}", name, mem.kind, mem.description);
        } else {
            let _ = writeln!(lines, "- {name}");
        }
    }
    lines
}