/// Access Evaluator: Orchestrate all access checks
///
/// Flow:
/// 1. Resolve roles from claims
/// 2. For each role, find matching rules
/// 3. For each rule, check verb + scope
/// 4. First match wins (allow), else deny

use std::sync::Arc;

use super::role_provider::RoleProvider;
use super::scope_checker::{CompositeScopeChecker, ScopeResult};
use super::types::{AccessDecision, Claims, DenyReason, ResourceMeta, Role, Verb};
pub use super::types::HasResourceMeta;

// ============================================================================
// Access Evaluator
// ============================================================================

/// Evaluates access requests against roles and scopes
pub struct AccessEvaluator {
    role_provider: Arc<dyn RoleProvider>,
    scope_checker: CompositeScopeChecker,
}

impl AccessEvaluator {
    pub fn new(role_provider: Arc<dyn RoleProvider>) -> Self {
        Self {
            role_provider,
            scope_checker: CompositeScopeChecker::new(),
        }
    }

    /// Custom scope checker
    pub fn with_scope_checker(mut self, checker: CompositeScopeChecker) -> Self {
        self.scope_checker = checker;
        self
    }

    /// Evaluate access for a single resource
    pub async fn evaluate(
        &self,
        claims: &Claims,
        resource: &ResourceMeta,
        verb: Verb,
    ) -> AccessDecision {
        // Get all roles for this user
        let roles = match self.role_provider.get_roles(&claims.roles).await {
            Ok(roles) => roles,
            Err(_) => return AccessDecision::Deny { reason: DenyReason::NoMatchingRole },
        };

        if roles.is_empty() {
            return AccessDecision::Deny { reason: DenyReason::NoMatchingRole };
        }

        // Check each role
        for role in &roles {
            if let Some(decision) = self.evaluate_role(claims, resource, verb, role) {
                if decision.is_allowed() {
                    return decision;
                }
            }
        }

        AccessDecision::Deny { reason: DenyReason::NoMatchingRule }
    }

    /// Evaluate a single role
    fn evaluate_role(
        &self,
        claims: &Claims,
        resource: &ResourceMeta,
        verb: Verb,
        role: &Role,
    ) -> Option<AccessDecision> {
        // Find rules that match the resource type
        let matching_rules = role.rules_for_resource(resource.resource_type);
        
        for (rule_idx, rule) in matching_rules.iter().enumerate() {
            // Check verb
            if !rule.allows_verb(verb) {
                continue;
            }

            // Check scope
            match self.scope_checker.check_all(claims, resource, &rule.scope) {
                ScopeResult::Pass | ScopeResult::NotApplicable => {
                    return Some(AccessDecision::Allow {
                        matched_role: role.name.clone(),
                        matched_rule_index: rule_idx,
                    });
                }
                ScopeResult::Fail(_) => continue,
            }
        }

        None
    }

    /// Evaluate capability-level access (without specific resource)
    /// Used for HTTP endpoint checks like "can user read anything?"
    pub async fn evaluate_capability(&self, claims: &Claims, verb: Verb) -> bool {
        let roles = match self.role_provider.get_roles(&claims.roles).await {
            Ok(roles) => roles,
            Err(_) => return false,
        };

        for role in &roles {
            for rule in &role.rules {
                if rule.allows_verb(verb) {
                    return true;
                }
            }
        }

        false
    }

    /// Filter resources by access
    pub async fn filter<T: HasResourceMeta>(
        &self,
        claims: &Claims,
        verb: Verb,
        resources: Vec<T>,
    ) -> FilterResult<T> {
        let mut allowed = Vec::new();
        let mut denied = Vec::new();

        for resource in resources {
            let meta = resource.resource_meta();
            match self.evaluate(claims, meta, verb).await {
                AccessDecision::Allow { .. } => allowed.push(resource),
                AccessDecision::Deny { reason } => {
                    denied.push((meta.id.clone(), reason));
                }
            }
        }

        FilterResult { allowed, denied }
    }

    /// Batch evaluation for multiple resources (optimized)
    pub async fn evaluate_batch(
        &self,
        claims: &Claims,
        resources: &[ResourceMeta],
        verb: Verb,
    ) -> Vec<AccessDecision> {
        // Pre-fetch roles once
        let roles = match self.role_provider.get_roles(&claims.roles).await {
            Ok(roles) => roles,
            Err(_) => {
                return resources
                    .iter()
                    .map(|_| AccessDecision::Deny { reason: DenyReason::NoMatchingRole })
                    .collect();
            }
        };

        if roles.is_empty() {
            return resources
                .iter()
                .map(|_| AccessDecision::Deny { reason: DenyReason::NoMatchingRole })
                .collect();
        }

        resources
            .iter()
            .map(|resource| {
                for role in &roles {
                    if let Some(decision) = self.evaluate_role(claims, resource, verb, role) {
                        if decision.is_allowed() {
                            return decision;
                        }
                    }
                }
                AccessDecision::Deny { reason: DenyReason::NoMatchingRule }
            })
            .collect()
    }
}

/// Result of filtering resources by access
#[derive(Debug)]
pub struct FilterResult<T> {
    pub allowed: Vec<T>,
    pub denied: Vec<(String, DenyReason)>,
}

impl<T> FilterResult<T> {
    pub fn all_allowed(&self) -> bool {
        self.denied.is_empty()
    }

    pub fn none_allowed(&self) -> bool {
        self.allowed.is_empty()
    }

    pub fn stats(&self) -> (usize, usize) {
        (self.allowed.len(), self.denied.len())
    }
}

// ============================================================================
// Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;
    use crate::rbac::role_provider::{admin_role, authenticated_user_role, portfolio_agent_role, InMemoryRoleProvider};
    use crate::rbac::types::{AccessRule, AccessScope, ResourceType, Visibility};

    fn test_provider() -> Arc<InMemoryRoleProvider> {
        Arc::new(
            InMemoryRoleProvider::new()
                .add_role(admin_role())
                .add_role(portfolio_agent_role())
                .add_role(authenticated_user_role())
        )
    }

    // ========================================================================
    // Admin Tests
    // ========================================================================

    #[tokio::test]
    async fn test_admin_full_access() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("root").with_roles(vec!["admin"]);

        let wiki = ResourceMeta::wiki("doc-1", "secret-project")
            .with_visibility(Visibility::Private);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Write).await;
        assert!(result.is_allowed());
    }

    #[tokio::test]
    async fn test_admin_delete_conversation() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("root").with_roles(vec!["admin"]);

        let conv = ResourceMeta::conversation("conv-1", "portfolio", "other-user");

        let result = evaluator.evaluate(&claims, &conv, Verb::Delete).await;
        assert!(result.is_allowed());
    }

    // ========================================================================
    // Portfolio Agent Tests
    // ========================================================================

    #[tokio::test]
    async fn test_portfolio_agent_read_public_wiki() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let wiki = ResourceMeta::wiki("doc-1", "homelab")
            .with_visibility(Visibility::Public);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_allowed());
    }

    #[tokio::test]
    async fn test_portfolio_agent_denied_private_wiki() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let wiki = ResourceMeta::wiki("secret", "homelab")
            .with_visibility(Visibility::Private);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_denied());
    }

    #[tokio::test]
    async fn test_portfolio_agent_denied_wrong_project() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let wiki = ResourceMeta::wiki("doc-1", "secret-project")
            .with_visibility(Visibility::Public);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_denied());
    }

    #[tokio::test]
    async fn test_portfolio_agent_own_conversation() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor-123").with_roles(vec!["portfolio-agent"]);

        let conv = ResourceMeta::conversation("conv-1", "portfolio", "visitor-123");

        let result = evaluator.evaluate(&claims, &conv, Verb::Write).await;
        assert!(result.is_allowed());
    }

    #[tokio::test]
    async fn test_portfolio_agent_denied_other_conversation() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor-123").with_roles(vec!["portfolio-agent"]);

        let conv = ResourceMeta::conversation("conv-1", "portfolio", "other-user");

        let result = evaluator.evaluate(&claims, &conv, Verb::Read).await;
        assert!(result.is_denied());
    }

    #[tokio::test]
    async fn test_portfolio_agent_denied_write_wiki() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let wiki = ResourceMeta::wiki("doc-1", "homelab")
            .with_visibility(Visibility::Public);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Write).await;
        assert!(result.is_denied());
    }

    // ========================================================================
    // Authenticated User Tests
    // ========================================================================

    #[tokio::test]
    async fn test_auth_user_read_any_wiki() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("alice").with_roles(vec!["authenticated-user"]);

        // Can read private wiki in any project
        let wiki = ResourceMeta::wiki("secret", "secret-project")
            .with_visibility(Visibility::Private);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_allowed());
    }

    #[tokio::test]
    async fn test_auth_user_own_conversation() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("alice").with_roles(vec!["authenticated-user"]);

        let conv = ResourceMeta::conversation("conv-1", "any-project", "alice");

        // Can read, write, delete own conversations
        assert!(evaluator.evaluate(&claims, &conv, Verb::Read).await.is_allowed());
        assert!(evaluator.evaluate(&claims, &conv, Verb::Write).await.is_allowed());
        assert!(evaluator.evaluate(&claims, &conv, Verb::Delete).await.is_allowed());
    }

    // ========================================================================
    // No Role Tests
    // ========================================================================

    #[tokio::test]
    async fn test_no_role_denied() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("anonymous"); // No roles

        let wiki = ResourceMeta::wiki("public", "homelab")
            .with_visibility(Visibility::Public);

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_denied());
        assert!(matches!(result, AccessDecision::Deny { reason: DenyReason::NoMatchingRole }));
    }

    #[tokio::test]
    async fn test_unknown_role_denied() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("user").with_roles(vec!["nonexistent-role"]);

        let wiki = ResourceMeta::wiki("public", "homelab");

        let result = evaluator.evaluate(&claims, &wiki, Verb::Read).await;
        assert!(result.is_denied());
    }

    // ========================================================================
    // Capability Tests
    // ========================================================================

    #[tokio::test]
    async fn test_capability_admin_can_write() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("root").with_roles(vec!["admin"]);

        assert!(evaluator.evaluate_capability(&claims, Verb::Write).await);
        assert!(evaluator.evaluate_capability(&claims, Verb::Delete).await);
    }

    #[tokio::test]
    async fn test_capability_portfolio_agent_read_only() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        assert!(evaluator.evaluate_capability(&claims, Verb::Read).await);
        assert!(evaluator.evaluate_capability(&claims, Verb::Query).await);
        assert!(evaluator.evaluate_capability(&claims, Verb::Write).await); // Has write for conversations
        assert!(!evaluator.evaluate_capability(&claims, Verb::Delete).await);
    }

    // ========================================================================
    // Filter Tests
    // ========================================================================

    #[tokio::test]
    async fn test_filter_resources() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let resources = vec![
            ResourceMeta::wiki("public-1", "homelab").with_visibility(Visibility::Public),
            ResourceMeta::wiki("private-1", "homelab").with_visibility(Visibility::Private),
            ResourceMeta::wiki("public-2", "portfolio").with_visibility(Visibility::Public),
            ResourceMeta::wiki("wrong-project", "secret").with_visibility(Visibility::Public),
        ];

        let result = evaluator.filter(&claims, Verb::Read, resources).await;

        assert_eq!(result.allowed.len(), 2); // public-1, public-2
        assert_eq!(result.denied.len(), 2); // private-1, wrong-project
    }

    // ========================================================================
    // Batch Evaluation Tests
    // ========================================================================

    #[tokio::test]
    async fn test_batch_evaluation() {
        let evaluator = AccessEvaluator::new(test_provider());
        let claims = Claims::new("visitor").with_roles(vec!["portfolio-agent"]);

        let resources = vec![
            ResourceMeta::wiki("public", "homelab").with_visibility(Visibility::Public),
            ResourceMeta::wiki("private", "homelab").with_visibility(Visibility::Private),
        ];

        let decisions = evaluator.evaluate_batch(&claims, &resources, Verb::Read).await;

        assert_eq!(decisions.len(), 2);
        assert!(decisions[0].is_allowed());
        assert!(decisions[1].is_denied());
    }

    // ========================================================================
    // Multiple Roles Tests
    // ========================================================================

    #[tokio::test]
    async fn test_multiple_roles_combined() {
        let evaluator = AccessEvaluator::new(test_provider());
        
        // User with both portfolio-agent and authenticated-user roles
        let claims = Claims::new("power-user")
            .with_roles(vec!["portfolio-agent", "authenticated-user"]);

        // Private wiki - denied by portfolio-agent, allowed by authenticated-user
        let private_wiki = ResourceMeta::wiki("secret", "homelab")
            .with_visibility(Visibility::Private);

        let result = evaluator.evaluate(&claims, &private_wiki, Verb::Read).await;
        assert!(result.is_allowed()); // authenticated-user allows it
    }
}