use crate::config::ProjectConfig;
use crate::http::context::{AppContext, OpenApiResult, bad_request};
use crate::worktree;
use poem_openapi::{Object, OpenApi, Tags, param::Path, payload::Json};
use serde::Serialize;
use std::path;
use std::sync::Arc;

#[derive(Tags)]
enum AgentsTags {
    Agents,
}

#[derive(Object)]
struct StartAgentPayload {
    story_id: String,
    agent_name: Option<String>,
}

#[derive(Object)]
struct StopAgentPayload {
    story_id: String,
    agent_name: String,
}

#[derive(Object, Serialize)]
struct AgentInfoResponse {
    story_id: String,
    agent_name: String,
    status: String,
    session_id: Option<String>,
    worktree_path: Option<String>,
}

#[derive(Object, Serialize)]
struct AgentConfigInfoResponse {
    name: String,
    role: String,
    model: Option<String>,
    allowed_tools: Option<Vec<String>>,
    max_turns: Option<u32>,
    max_budget_usd: Option<f64>,
}

#[derive(Object)]
struct CreateWorktreePayload {
    story_id: String,
}

#[derive(Object, Serialize)]
struct WorktreeInfoResponse {
    story_id: String,
    worktree_path: String,
    branch: String,
    base_branch: String,
}

#[derive(Object, Serialize)]
struct WorktreeListEntry {
    story_id: String,
    path: String,
}

/// Returns true if the story file exists in `work/5_archived/`.
///
/// Used to exclude agents for already-archived stories from the `list_agents`
/// response so the agents panel is not cluttered with old completed items on
/// frontend startup.
fn story_is_archived(project_root: &path::Path, story_id: &str) -> bool {
    project_root
        .join(".story_kit")
        .join("work")
        .join("5_archived")
        .join(format!("{story_id}.md"))
        .exists()
}

pub struct AgentsApi {
    pub ctx: Arc<AppContext>,
}

#[OpenApi(tag = "AgentsTags::Agents")]
impl AgentsApi {
    /// Start an agent for a given story (creates worktree, runs setup, spawns agent).
    /// If agent_name is omitted, the first configured agent is used.
    #[oai(path = "/agents/start", method = "post")]
    async fn start_agent(
        &self,
        payload: Json<StartAgentPayload>,
    ) -> OpenApiResult<Json<AgentInfoResponse>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let info = self
            .ctx
            .agents
            .start_agent(
                &project_root,
                &payload.0.story_id,
                payload.0.agent_name.as_deref(),
                None,
            )
            .await
            .map_err(bad_request)?;

        Ok(Json(AgentInfoResponse {
            story_id: info.story_id,
            agent_name: info.agent_name,
            status: info.status.to_string(),
            session_id: info.session_id,
            worktree_path: info.worktree_path,
        }))
    }

    /// Stop a running agent and clean up its worktree.
    #[oai(path = "/agents/stop", method = "post")]
    async fn stop_agent(&self, payload: Json<StopAgentPayload>) -> OpenApiResult<Json<bool>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        self.ctx
            .agents
            .stop_agent(
                &project_root,
                &payload.0.story_id,
                &payload.0.agent_name,
            )
            .await
            .map_err(bad_request)?;

        Ok(Json(true))
    }

    /// List all agents with their status.
    ///
    /// Agents for stories that have been archived (`work/5_archived/`) are
    /// excluded so the agents panel is not cluttered with old completed items
    /// on frontend startup.
    #[oai(path = "/agents", method = "get")]
    async fn list_agents(&self) -> OpenApiResult<Json<Vec<AgentInfoResponse>>> {
        let project_root = self.ctx.agents.get_project_root(&self.ctx.state).ok();
        let agents = self.ctx.agents.list_agents().map_err(bad_request)?;

        Ok(Json(
            agents
                .into_iter()
                .filter(|info| {
                    project_root
                        .as_deref()
                        .map(|root| !story_is_archived(root, &info.story_id))
                        .unwrap_or(true)
                })
                .map(|info| AgentInfoResponse {
                    story_id: info.story_id,
                    agent_name: info.agent_name,
                    status: info.status.to_string(),
                    session_id: info.session_id,
                    worktree_path: info.worktree_path,
                })
                .collect(),
        ))
    }

    /// Get the configured agent roster from project.toml.
    #[oai(path = "/agents/config", method = "get")]
    async fn get_agent_config(
        &self,
    ) -> OpenApiResult<Json<Vec<AgentConfigInfoResponse>>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let config = ProjectConfig::load(&project_root).map_err(bad_request)?;

        Ok(Json(
            config
                .agent
                .iter()
                .map(|a| AgentConfigInfoResponse {
                    name: a.name.clone(),
                    role: a.role.clone(),
                    model: a.model.clone(),
                    allowed_tools: a.allowed_tools.clone(),
                    max_turns: a.max_turns,
                    max_budget_usd: a.max_budget_usd,
                })
                .collect(),
        ))
    }

    /// Reload project config and return the updated agent roster.
    #[oai(path = "/agents/config/reload", method = "post")]
    async fn reload_config(
        &self,
    ) -> OpenApiResult<Json<Vec<AgentConfigInfoResponse>>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let config = ProjectConfig::load(&project_root).map_err(bad_request)?;

        Ok(Json(
            config
                .agent
                .iter()
                .map(|a| AgentConfigInfoResponse {
                    name: a.name.clone(),
                    role: a.role.clone(),
                    model: a.model.clone(),
                    allowed_tools: a.allowed_tools.clone(),
                    max_turns: a.max_turns,
                    max_budget_usd: a.max_budget_usd,
                })
                .collect(),
        ))
    }

    /// Create a git worktree for a story under .story_kit/worktrees/{story_id}.
    #[oai(path = "/agents/worktrees", method = "post")]
    async fn create_worktree(
        &self,
        payload: Json<CreateWorktreePayload>,
    ) -> OpenApiResult<Json<WorktreeInfoResponse>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let info = self
            .ctx
            .agents
            .create_worktree(&project_root, &payload.0.story_id)
            .await
            .map_err(bad_request)?;

        Ok(Json(WorktreeInfoResponse {
            story_id: payload.0.story_id,
            worktree_path: info.path.to_string_lossy().to_string(),
            branch: info.branch,
            base_branch: info.base_branch,
        }))
    }

    /// List all worktrees under .story_kit/worktrees/.
    #[oai(path = "/agents/worktrees", method = "get")]
    async fn list_worktrees(&self) -> OpenApiResult<Json<Vec<WorktreeListEntry>>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let entries = worktree::list_worktrees(&project_root).map_err(bad_request)?;

        Ok(Json(
            entries
                .into_iter()
                .map(|e| WorktreeListEntry {
                    story_id: e.story_id,
                    path: e.path.to_string_lossy().to_string(),
                })
                .collect(),
        ))
    }

    /// Remove a git worktree and its feature branch for a story.
    #[oai(path = "/agents/worktrees/:story_id", method = "delete")]
    async fn remove_worktree(&self, story_id: Path<String>) -> OpenApiResult<Json<bool>> {
        let project_root = self
            .ctx
            .agents
            .get_project_root(&self.ctx.state)
            .map_err(bad_request)?;

        let config = ProjectConfig::load(&project_root).map_err(bad_request)?;
        worktree::remove_worktree_by_story_id(&project_root, &story_id.0, &config)
            .await
            .map_err(bad_request)?;

        Ok(Json(true))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::agents::AgentStatus;
    use tempfile::TempDir;

    fn make_archived_dir(tmp: &TempDir) -> path::PathBuf {
        let root = tmp.path().to_path_buf();
        let archived = root
            .join(".story_kit")
            .join("work")
            .join("5_archived");
        std::fs::create_dir_all(&archived).unwrap();
        root
    }

    #[test]
    fn story_is_archived_false_when_file_absent() {
        let tmp = TempDir::new().unwrap();
        let root = make_archived_dir(&tmp);
        assert!(!story_is_archived(&root, "79_story_foo"));
    }

    #[test]
    fn story_is_archived_true_when_file_present() {
        let tmp = TempDir::new().unwrap();
        let root = make_archived_dir(&tmp);
        std::fs::write(
            root.join(".story_kit/work/5_archived/79_story_foo.md"),
            "---\nname: test\n---\n",
        )
        .unwrap();
        assert!(story_is_archived(&root, "79_story_foo"));
    }

    #[tokio::test]
    async fn list_agents_excludes_archived_stories() {
        let tmp = TempDir::new().unwrap();
        let root = make_archived_dir(&tmp);

        // Place an archived story file
        std::fs::write(
            root.join(".story_kit/work/5_archived/79_story_archived.md"),
            "---\nname: archived story\n---\n",
        )
        .unwrap();

        let ctx = AppContext::new_test(root);
        // Inject an agent for the archived story (completed) and one for an active story
        ctx.agents
            .inject_test_agent("79_story_archived", "coder-1", AgentStatus::Completed);
        ctx.agents
            .inject_test_agent("80_story_active", "coder-1", AgentStatus::Running);

        let api = AgentsApi {
            ctx: Arc::new(ctx),
        };
        let result = api.list_agents().await.unwrap().0;

        // Archived story's agent should not appear
        assert!(
            !result.iter().any(|a| a.story_id == "79_story_archived"),
            "archived story agent should be excluded from list_agents"
        );
        // Active story's agent should still appear
        assert!(
            result.iter().any(|a| a.story_id == "80_story_active"),
            "active story agent should be included in list_agents"
        );
    }

    #[tokio::test]
    async fn list_agents_includes_all_when_no_project_root() {
        // When no project root is configured, all agents are returned (safe default).
        let tmp = TempDir::new().unwrap();
        let ctx = AppContext::new_test(tmp.path().to_path_buf());
        // Clear the project_root so get_project_root returns Err
        *ctx.state.project_root.lock().unwrap() = None;
        ctx.agents
            .inject_test_agent("42_story_whatever", "coder-1", AgentStatus::Completed);

        let api = AgentsApi {
            ctx: Arc::new(ctx),
        };
        let result = api.list_agents().await.unwrap().0;
        assert!(result.iter().any(|a| a.story_id == "42_story_whatever"));
    }
}