//! Permission checking utilities for API endpoints.
//!
//! Provides reusable functions to check user permissions against the role system.

use axum::http::StatusCode;
use sqlx::PgPool;
use uuid::Uuid;

/// Check if a user has a specific permission, optionally within a community scope.
pub async fn user_has_permission(
    pool: &PgPool,
    user_id: Uuid,
    permission: &str,
    community_id: Option<Uuid>,
) -> Result<bool, (StatusCode, String)> {
    let has_perm = sqlx::query_scalar!(
        "SELECT user_has_permission($1, $2, $3)",
        user_id,
        permission,
        community_id
    )
    .fetch_one(pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?
    .unwrap_or(false);

    Ok(has_perm)
}

/// Require a permission, returning Forbidden error if not granted.
pub async fn require_permission(
    pool: &PgPool,
    user_id: Uuid,
    permission: &str,
    community_id: Option<Uuid>,
) -> Result<(), (StatusCode, String)> {
    if !user_has_permission(pool, user_id, permission, community_id).await? {
        return Err((
            StatusCode::FORBIDDEN,
            format!("Permission '{}' required", permission),
        ));
    }
    Ok(())
}

/// Require any of the given permissions.
pub async fn require_any_permission(
    pool: &PgPool,
    user_id: Uuid,
    permissions: &[&str],
    community_id: Option<Uuid>,
) -> Result<(), (StatusCode, String)> {
    for perm in permissions {
        if user_has_permission(pool, user_id, perm, community_id).await? {
            return Ok(());
        }
    }
    Err((
        StatusCode::FORBIDDEN,
        format!("One of these permissions required: {}", permissions.join(", ")),
    ))
}

/// Check if user is a platform admin (has platform.admin permission).
#[allow(dead_code)]
pub async fn is_platform_admin(
    pool: &PgPool,
    user_id: Uuid,
) -> Result<bool, (StatusCode, String)> {
    user_has_permission(pool, user_id, "platform.admin", None).await
}

/// Require platform admin access.
#[allow(dead_code)]
pub async fn require_platform_admin(
    pool: &PgPool,
    user_id: Uuid,
) -> Result<(), (StatusCode, String)> {
    require_permission(pool, user_id, "platform.admin", None).await
}

/// Check if user is a community admin or moderator.
#[allow(dead_code)]
pub async fn is_community_staff(
    pool: &PgPool,
    user_id: Uuid,
    community_id: Uuid,
) -> Result<bool, (StatusCode, String)> {
    let is_admin = user_has_permission(pool, user_id, "community.admin", Some(community_id)).await?;
    if is_admin {
        return Ok(true);
    }
    user_has_permission(pool, user_id, "community.moderate", Some(community_id)).await
}

/// Permission constants for common operations.
/// Used throughout API handlers for authorization.
pub mod perms {
    // Platform-level
    pub const PLATFORM_ADMIN: &str = "platform.admin";
    pub const PLATFORM_SETTINGS: &str = "platform.settings";
    pub const PLATFORM_PLUGINS: &str = "platform.plugins";
    
    // Community-level
    pub const COMMUNITY_CREATE: &str = "community.create";
    pub const COMMUNITY_ADMIN: &str = "community.admin";
    pub const COMMUNITY_SETTINGS: &str = "community.settings";
    pub const COMMUNITY_MODERATE: &str = "community.moderate";
    
    // Proposals
    pub const PROPOSAL_CREATE: &str = "proposal.create";
    pub const PROPOSAL_EDIT_OWN: &str = "proposal.edit_own";
    pub const PROPOSAL_EDIT_ANY: &str = "proposal.edit_any";
    pub const PROPOSAL_DELETE_OWN: &str = "proposal.delete_own";
    pub const PROPOSAL_DELETE_ANY: &str = "proposal.delete_any";
    pub const PROPOSAL_MANAGE_STATUS: &str = "proposal.manage_status";
    
    // Voting
    pub const VOTE_CAST: &str = "vote.cast";
    pub const VOTE_VIEW_RESULTS: &str = "vote.view_results";
    pub const VOTING_CONFIG: &str = "voting.configure";
    
    // Moderation
    pub const MOD_BAN_USERS: &str = "moderation.ban_users";
    pub const MOD_REMOVE_CONTENT: &str = "moderation.remove_content";
    pub const MOD_VIEW_REPORTS: &str = "moderation.view_reports";
    
    // Users
    pub const USER_MANAGE: &str = "users.manage";
    pub const USER_INVITE: &str = "users.invite";
}