//! The IdeA MCP **tool catalogue** and the tool → [`OrchestratorRequest`] mapping.
//!
//! Each tool here is a thin, typed face over an **already-existing**
//! [`OrchestratorCommand`] (cadrage Décision 4, principe directeur : « le serveur
//! MCP n'invente aucune sémantique »). The mapping builds an
//! [`OrchestratorRequest`] from the tool arguments and lets
//! [`OrchestratorRequest::validate`] be the **single source of truth** for
//! validation — the very same path the filesystem watcher takes. No tool
//! validates anything itself; no tool reaches a use case directly.
//!
//! ## Agent discovery (`idea_list_agents`)
//!
//! Discovery maps to the [`OrchestratorCommand::ListAgents`] domain variant and is
//! served through the **same** `OrchestratorService::dispatch` as every other tool
//! (no use-case is reached directly). Its success carries the agent list inline as
//! a JSON array in the outcome's reply — see [`tool_returns_reply`].

use domain::{OrchestratorCommand, OrchestratorError, OrchestratorRequest};
use serde_json::{json, Value};

/// A tool the IdeA MCP server advertises, with the JSON Schema MCP clients read
/// from `tools/list`.
pub struct ToolDef {
    /// Tool name as seen by the agent (`idea_ask_agent`, …).
    pub name: &'static str,
    /// One-line human description shown in the client.
    pub description: &'static str,
    /// JSON Schema (object) for the tool's arguments.
    pub input_schema: Value,
}

/// Errors mapping a tool call into a validated [`OrchestratorCommand`].
#[derive(Debug, thiserror::Error, PartialEq, Eq)]
pub enum ToolMapError {
    /// The tool name is not one this server exposes.
    #[error("unknown tool: {0}")]
    UnknownTool(String),
    /// The `arguments` object was absent or not a JSON object.
    #[error("tool `{0}` arguments must be a JSON object")]
    BadArguments(String),
    /// The arguments did not satisfy the underlying command's invariants.
    #[error(transparent)]
    Invalid(#[from] OrchestratorError),
}

/// Whether a successful call of `tool` carries an inline reply payload back to the
/// caller: `idea_ask_agent` (the target's `Final`) and `idea_list_agents` (the
/// agent list as a JSON array).
#[must_use]
pub fn tool_returns_reply(tool: &str) -> bool {
    matches!(tool, "idea_ask_agent" | "idea_list_agents")
}

/// The full catalogue advertised on `tools/list`.
///
/// Exactly the tools whose mapping target already exists as an
/// [`OrchestratorCommand`].
#[must_use]
pub fn catalogue() -> Vec<ToolDef> {
    vec![
        ToolDef {
            name: "idea_list_agents",
            description: "List the IdeA agents declared in the project's manifest. Returns the \
                          agents inline as a JSON array (id, name, profile, origin, …).",
            input_schema: json!({
                "type": "object",
                "properties": {},
                "additionalProperties": false
            }),
        },
        ToolDef {
            name: "idea_ask_agent",
            description: "Ask another IdeA agent a task and wait for its reply (synchronous \
                          inter-agent rendezvous). Returns the target agent's answer inline.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "target": { "type": "string", "description": "Target agent display name." },
                    "task": { "type": "string", "description": "The task/message to send." }
                },
                "required": ["target", "task"],
                "additionalProperties": false
            }),
        },
        ToolDef {
            name: "idea_launch_agent",
            description: "Launch (or attach) an IdeA agent. Fire-and-forget: returns once IdeA \
                          has started the agent, without waiting for any work.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "target": { "type": "string", "description": "Target agent display name." },
                    "profile": { "type": "string", "description": "Optional profile reference for a not-yet-created agent." },
                    "task": { "type": "string", "description": "Optional initial task/context for the launched agent." },
                    "visibility": { "type": "string", "enum": ["background", "visible"], "description": "Where to place the session (default background)." },
                    "nodeId": { "type": "string", "description": "Target layout cell id, required when visibility is \"visible\"." }
                },
                "required": ["target"],
                "additionalProperties": false
            }),
        },
        ToolDef {
            name: "idea_stop_agent",
            description: "Stop a running IdeA agent by killing its terminal session.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "target": { "type": "string", "description": "Target agent display name." }
                },
                "required": ["target"],
                "additionalProperties": false
            }),
        },
        ToolDef {
            name: "idea_update_context",
            description: "Overwrite an IdeA agent's `.md` context with a new Markdown body.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "target": { "type": "string", "description": "Target agent display name." },
                    "context": { "type": "string", "description": "New Markdown body." }
                },
                "required": ["target", "context"],
                "additionalProperties": false
            }),
        },
        ToolDef {
            name: "idea_create_skill",
            description: "Create a reusable IdeA skill (Markdown) in the project or global scope.",
            input_schema: json!({
                "type": "object",
                "properties": {
                    "name": { "type": "string", "description": "Skill name (also the .md stem)." },
                    "context": { "type": "string", "description": "Markdown body of the skill." },
                    "scope": { "type": "string", "enum": ["project", "global"], "description": "Scope (default project)." }
                },
                "required": ["name", "context"],
                "additionalProperties": false
            }),
        },
    ]
}

/// Maps an MCP `tools/call` (`name` + `arguments`) to a validated
/// [`OrchestratorCommand`], reusing [`OrchestratorRequest::validate`] as the one
/// validation authority.
///
/// `arguments` is the raw object an MCP client passes under `params.arguments`.
///
/// # Errors
/// - [`ToolMapError::UnknownTool`] for a name outside [`catalogue`],
/// - [`ToolMapError::BadArguments`] when `arguments` is not an object,
/// - [`ToolMapError::Invalid`] when the underlying command's invariants fail.
pub fn map_tool_call(
    name: &str,
    arguments: &Value,
) -> Result<OrchestratorCommand, ToolMapError> {
    let args = arguments
        .as_object()
        .ok_or_else(|| ToolMapError::BadArguments(name.to_owned()))?;

    // Small helpers to pull optional string fields out of the arguments object.
    let s = |key: &str| -> Option<String> {
        args.get(key).and_then(Value::as_str).map(str::to_owned)
    };

    // Translate the tool into the wire-level request shape the watcher already
    // uses (v2 `type`), then let `validate` enforce the invariants once.
    let request = match name {
        "idea_list_agents" => OrchestratorRequest {
            request_type: Some("agent.list".to_owned()),
            ..base()
        },
        "idea_ask_agent" => OrchestratorRequest {
            request_type: Some("agent.message".to_owned()),
            target_agent: s("target"),
            task: s("task"),
            ..base()
        },
        "idea_launch_agent" => OrchestratorRequest {
            request_type: Some("agent.run".to_owned()),
            target_agent: s("target"),
            profile: s("profile"),
            task: s("task"),
            visibility: s("visibility"),
            node_id: parse_node_id(args.get("nodeId")),
            ..base()
        },
        "idea_stop_agent" => OrchestratorRequest {
            request_type: Some("agent.stop".to_owned()),
            target_agent: s("target"),
            ..base()
        },
        "idea_update_context" => OrchestratorRequest {
            request_type: Some("agent.update_context".to_owned()),
            target_agent: s("target"),
            context: s("context"),
            ..base()
        },
        "idea_create_skill" => OrchestratorRequest {
            request_type: Some("skill.create".to_owned()),
            name: s("name"),
            context: s("context"),
            scope: s("scope"),
            ..base()
        },
        other => return Err(ToolMapError::UnknownTool(other.to_owned())),
    };

    Ok(request.validate()?)
}

/// An all-`None` request to spread over; keeps each arm above to just its fields.
fn base() -> OrchestratorRequest {
    OrchestratorRequest {
        action: None,
        request_type: None,
        requested_by: None,
        name: None,
        target_agent: None,
        profile: None,
        context: None,
        task: None,
        visibility: None,
        node_id: None,
        attach_to_cell: None,
        scope: None,
    }
}

/// Parses an optional `nodeId` JSON value into a [`domain::NodeId`], silently
/// dropping a malformed/absent one (validation then rejects a `visible` launch
/// missing its node, with a precise field error).
fn parse_node_id(value: Option<&Value>) -> Option<domain::NodeId> {
    let raw = value?.as_str()?;
    uuid::Uuid::parse_str(raw).ok().map(domain::NodeId::from_uuid)
}

#[cfg(test)]
mod tests {
    use super::*;
    use domain::OrchestratorVisibility;

    #[test]
    fn ask_agent_maps_to_ask_command() {
        let cmd = map_tool_call(
            "idea_ask_agent",
            &json!({ "target": "Architect", "task": "Analyse §17" }),
        )
        .unwrap();
        assert_eq!(
            cmd,
            OrchestratorCommand::AskAgent {
                target: "Architect".to_owned(),
                task: "Analyse §17".to_owned(),
            }
        );
    }

    #[test]
    fn launch_agent_maps_to_spawn_background_by_default() {
        let cmd = map_tool_call("idea_launch_agent", &json!({ "target": "Dev" })).unwrap();
        assert_eq!(
            cmd,
            OrchestratorCommand::SpawnAgent {
                name: "Dev".to_owned(),
                profile: None,
                context: None,
                visibility: OrchestratorVisibility::Background,
            }
        );
    }

    #[test]
    fn stop_update_and_skill_map_to_their_commands() {
        assert_eq!(
            map_tool_call("idea_stop_agent", &json!({ "target": "Dev" })).unwrap(),
            OrchestratorCommand::StopAgent { name: "Dev".to_owned() }
        );
        assert_eq!(
            map_tool_call(
                "idea_update_context",
                &json!({ "target": "Dev", "context": "# body" })
            )
            .unwrap(),
            OrchestratorCommand::UpdateAgentContext {
                name: "Dev".to_owned(),
                context: "# body".to_owned(),
            }
        );
        assert_eq!(
            map_tool_call(
                "idea_create_skill",
                &json!({ "name": "deploy", "context": "# steps" })
            )
            .unwrap(),
            OrchestratorCommand::CreateSkill {
                name: "deploy".to_owned(),
                content: "# steps".to_owned(),
                scope: domain::SkillScope::Project,
            }
        );
    }

    #[test]
    fn missing_required_field_surfaces_validation_error() {
        let err = map_tool_call("idea_ask_agent", &json!({ "target": "Architect" }));
        assert!(matches!(err, Err(ToolMapError::Invalid(_))));
    }

    #[test]
    fn list_agents_maps_to_list_command() {
        let cmd = map_tool_call("idea_list_agents", &json!({})).unwrap();
        assert_eq!(cmd, OrchestratorCommand::ListAgents);
    }

    #[test]
    fn unknown_tool_is_rejected() {
        let err = map_tool_call("idea_made_up_tool", &json!({}));
        assert_eq!(
            err,
            Err(ToolMapError::UnknownTool("idea_made_up_tool".to_owned()))
        );
    }

    #[test]
    fn non_object_arguments_are_rejected() {
        let err = map_tool_call("idea_ask_agent", &json!("nope"));
        assert_eq!(
            err,
            Err(ToolMapError::BadArguments("idea_ask_agent".to_owned()))
        );
    }
}