use std::sync::Arc;

use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use sqlx::PgPool;
use uuid::Uuid;

use crate::plugins::{
    hooks::{HookContext, PluginError},
    manager::{Plugin, PluginMetadata, PluginScope, PluginSystem},
};

/// Moderation Ledger Plugin
/// 
/// Creates an immutable, cryptographically-chained log of all moderation decisions.
/// This plugin is NON-DEACTIVATABLE by design - transparency is not optional.
/// 
/// Features:
/// - Immutable entries with SHA-256 hash chain
/// - Full audit trail with actor, target, reason, evidence
/// - Chain verification for tamper detection
/// - Export to JSON/CSV
/// - Community-scoped with independent chains
pub struct ModerationLedgerPlugin;

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum ModerationActionType {
    // Content moderation
    ContentRemove,
    ContentHide,
    ContentRestore,
    ContentEdit,
    ContentFlag,
    ContentUnflag,
    
    // User moderation
    UserWarn,
    UserMute,
    UserUnmute,
    UserSuspend,
    UserUnsuspend,
    UserBan,
    UserUnban,
    UserRoleChange,
    
    // Community moderation
    CommunitySettingChange,
    CommunityRuleAdd,
    CommunityRuleEdit,
    CommunityRuleRemove,
    
    // Proposal/voting moderation
    ProposalClose,
    ProposalReopen,
    ProposalArchive,
    VoteInvalidate,
    VoteRestore,
    
    // Escalation
    EscalateToAdmin,
    EscalateToCommunity,
    AppealReceived,
    AppealResolved,
}

impl ModerationActionType {
    pub fn as_db_str(&self) -> &'static str {
        match self {
            Self::ContentRemove => "content_remove",
            Self::ContentHide => "content_hide",
            Self::ContentRestore => "content_restore",
            Self::ContentEdit => "content_edit",
            Self::ContentFlag => "content_flag",
            Self::ContentUnflag => "content_unflag",
            Self::UserWarn => "user_warn",
            Self::UserMute => "user_mute",
            Self::UserUnmute => "user_unmute",
            Self::UserSuspend => "user_suspend",
            Self::UserUnsuspend => "user_unsuspend",
            Self::UserBan => "user_ban",
            Self::UserUnban => "user_unban",
            Self::UserRoleChange => "user_role_change",
            Self::CommunitySettingChange => "community_setting_change",
            Self::CommunityRuleAdd => "community_rule_add",
            Self::CommunityRuleEdit => "community_rule_edit",
            Self::CommunityRuleRemove => "community_rule_remove",
            Self::ProposalClose => "proposal_close",
            Self::ProposalReopen => "proposal_reopen",
            Self::ProposalArchive => "proposal_archive",
            Self::VoteInvalidate => "vote_invalidate",
            Self::VoteRestore => "vote_restore",
            Self::EscalateToAdmin => "escalate_to_admin",
            Self::EscalateToCommunity => "escalate_to_community",
            Self::AppealReceived => "appeal_received",
            Self::AppealResolved => "appeal_resolved",
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct LedgerEntry {
    pub id: Uuid,
    pub sequence_number: i64,
    pub community_id: Option<Uuid>,
    pub actor_user_id: Uuid,
    pub actor_role: String,
    pub action_type: String,
    pub target_type: String,
    pub target_id: Uuid,
    pub reason: String,
    pub rule_reference: Option<String>,
    pub evidence: Option<Value>,
    pub duration_hours: Option<i32>,
    pub decision_type: String,
    pub entry_hash: String,
    pub created_at: chrono::DateTime<chrono::Utc>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ChainVerificationResult {
    pub is_valid: bool,
    pub total_entries: i64,
    pub broken_at_sequence: Option<i64>,
    pub expected_hash: Option<String>,
    pub actual_hash: Option<String>,
    pub error_message: Option<String>,
}

/// Service for interacting with the moderation ledger
pub struct LedgerService;

impl LedgerService {
    /// Create a new ledger entry
    #[allow(clippy::too_many_arguments)]
    pub async fn create_entry(
        pool: &PgPool,
        community_id: Option<Uuid>,
        actor_user_id: Uuid,
        actor_role: &str,
        action_type: ModerationActionType,
        target_type: &str,
        target_id: Uuid,
        reason: &str,
        rule_reference: Option<&str>,
        evidence: Option<Value>,
        target_snapshot: Option<Value>,
        duration_hours: Option<i32>,
        decision_type: &str,
        vote_proposal_id: Option<Uuid>,
        vote_result: Option<Value>,
    ) -> Result<Uuid, PluginError> {
        let entry_id: Uuid = sqlx::query_scalar(
            r#"SELECT create_ledger_entry(
                $1, $2, $3, $4::moderation_action_type, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14
            )"#,
        )
        .bind(community_id)
        .bind(actor_user_id)
        .bind(actor_role)
        .bind(action_type.as_db_str())
        .bind(target_type)
        .bind(target_id)
        .bind(reason)
        .bind(rule_reference)
        .bind(evidence)
        .bind(target_snapshot)
        .bind(duration_hours)
        .bind(decision_type)
        .bind(vote_proposal_id)
        .bind(vote_result)
        .fetch_one(pool)
        .await?;

        Ok(entry_id)
    }

    /// Get ledger entries for a community
    pub async fn get_entries(
        pool: &PgPool,
        community_id: Option<Uuid>,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<LedgerEntry>, PluginError> {
        let entries = sqlx::query_as!(
            LedgerEntry,
            r#"SELECT 
                id,
                sequence_number,
                community_id,
                actor_user_id,
                actor_role,
                action_type::text AS "action_type!",
                target_type,
                target_id,
                reason,
                rule_reference,
                evidence,
                duration_hours,
                decision_type,
                entry_hash,
                created_at
            FROM moderation_ledger
            WHERE community_id IS NOT DISTINCT FROM $1
            ORDER BY sequence_number DESC
            LIMIT $2 OFFSET $3"#,
            community_id,
            limit,
            offset,
        )
        .fetch_all(pool)
        .await?;

        Ok(entries)
    }

    /// Get a single entry by ID
    pub async fn get_entry(pool: &PgPool, entry_id: Uuid) -> Result<Option<LedgerEntry>, PluginError> {
        let entry = sqlx::query_as!(
            LedgerEntry,
            r#"SELECT 
                id,
                sequence_number,
                community_id,
                actor_user_id,
                actor_role,
                action_type::text AS "action_type!",
                target_type,
                target_id,
                reason,
                rule_reference,
                evidence,
                duration_hours,
                decision_type,
                entry_hash,
                created_at
            FROM moderation_ledger
            WHERE id = $1"#,
            entry_id,
        )
        .fetch_optional(pool)
        .await?;

        Ok(entry)
    }

    /// Get entries targeting a specific entity
    pub async fn get_entries_for_target(
        pool: &PgPool,
        target_type: &str,
        target_id: Uuid,
    ) -> Result<Vec<LedgerEntry>, PluginError> {
        let entries = sqlx::query_as!(
            LedgerEntry,
            r#"SELECT 
                id,
                sequence_number,
                community_id,
                actor_user_id,
                actor_role,
                action_type::text AS "action_type!",
                target_type,
                target_id,
                reason,
                rule_reference,
                evidence,
                duration_hours,
                decision_type,
                entry_hash,
                created_at
            FROM moderation_ledger
            WHERE target_type = $1 AND target_id = $2
            ORDER BY sequence_number DESC"#,
            target_type,
            target_id,
        )
        .fetch_all(pool)
        .await?;

        Ok(entries)
    }

    /// Verify the chain integrity
    pub async fn verify_chain(
        pool: &PgPool,
        community_id: Option<Uuid>,
    ) -> Result<ChainVerificationResult, PluginError> {
        let result = sqlx::query!(
            r#"SELECT 
                is_valid,
                total_entries,
                broken_at_sequence,
                expected_hash,
                actual_hash,
                error_message
            FROM verify_ledger_chain($1)"#,
            community_id,
        )
        .fetch_one(pool)
        .await?;

        Ok(ChainVerificationResult {
            is_valid: result.is_valid.unwrap_or(false),
            total_entries: result.total_entries.unwrap_or(0),
            broken_at_sequence: result.broken_at_sequence,
            expected_hash: result.expected_hash,
            actual_hash: result.actual_hash,
            error_message: result.error_message,
        })
    }

    /// Get statistics for a community
    pub async fn get_stats(
        pool: &PgPool,
        community_id: Option<Uuid>,
    ) -> Result<Value, PluginError> {
        let stats = sqlx::query!(
            r#"SELECT 
                action_type::text AS action_type,
                decision_type,
                total_actions,
                unique_actors,
                unique_targets
            FROM v_moderation_stats
            WHERE community_id IS NOT DISTINCT FROM $1"#,
            community_id,
        )
        .fetch_all(pool)
        .await?;

        let summary: Vec<Value> = stats
            .into_iter()
            .map(|s| {
                json!({
                    "action_type": s.action_type,
                    "decision_type": s.decision_type,
                    "total_actions": s.total_actions,
                    "unique_actors": s.unique_actors,
                    "unique_targets": s.unique_targets,
                })
            })
            .collect();

        Ok(json!({ "stats": summary }))
    }

    /// Export ledger entries as JSON
    pub async fn export_json(
        pool: &PgPool,
        community_id: Option<Uuid>,
    ) -> Result<Value, PluginError> {
        let entries = Self::get_entries(pool, community_id, 100000, 0).await?;
        let verification = Self::verify_chain(pool, community_id).await?;

        Ok(json!({
            "export_version": "1.0",
            "exported_at": chrono::Utc::now(),
            "community_id": community_id,
            "chain_verification": verification,
            "entries": entries,
        }))
    }
}

#[async_trait]
impl Plugin for ModerationLedgerPlugin {
    fn metadata(&self) -> PluginMetadata {
        PluginMetadata {
            name: "moderation_ledger",
            version: "1.0.0",
            description: "Immutable, cryptographically-chained log of all moderation decisions. Cannot be deactivated.",
            is_core: true, // Core plugin - cannot be disabled
            scope: PluginScope::Global,
            default_enabled: true,
            settings_schema: Some(json!({
                "type": "object",
                "properties": {
                    "require_reason_min_length": {
                        "type": "integer",
                        "title": "Minimum reason length",
                        "description": "Minimum characters required for moderation justifications",
                        "default": 20,
                        "minimum": 10,
                        "maximum": 500
                    },
                    "require_rule_reference": {
                        "type": "boolean",
                        "title": "Require rule reference",
                        "description": "Require moderators to cite a specific community rule",
                        "default": false
                    },
                    "public_ledger": {
                        "type": "boolean",
                        "title": "Public ledger",
                        "description": "Allow all community members to view the moderation ledger",
                        "default": true
                    }
                }
            })),
        }
    }

    fn register(&self, system: &mut PluginSystem) {
        let plugin_name = self.metadata().name.to_string();

        // Hook: Log content removal
        system.add_action(
            "moderation.content_removed",
            plugin_name.clone(),
            1, // Highest priority - must log before anything else
            Arc::new(move |ctx: HookContext, payload: Value| {
                let plugin_name = plugin_name.clone();
                Box::pin(async move {
                    let actor_id = ctx.actor_user_id
                        .ok_or_else(|| PluginError::Message("Missing actor_user_id".into()))?;

                    let target_id = payload
                        .get("content_id")
                        .and_then(|v| v.as_str())
                        .and_then(|s| Uuid::parse_str(s).ok())
                        .ok_or_else(|| PluginError::Message("Missing content_id".into()))?;

                    let content_type = payload
                        .get("content_type")
                        .and_then(|v| v.as_str())
                        .unwrap_or("unknown");

                    let reason = payload
                        .get("reason")
                        .and_then(|v| v.as_str())
                        .unwrap_or("No reason provided");

                    let actor_role = payload
                        .get("actor_role")
                        .and_then(|v| v.as_str())
                        .unwrap_or("moderator");

                    let entry_id = LedgerService::create_entry(
                        &ctx.pool,
                        ctx.community_id,
                        actor_id,
                        actor_role,
                        ModerationActionType::ContentRemove,
                        content_type,
                        target_id,
                        reason,
                        payload.get("rule_reference").and_then(|v| v.as_str()),
                        payload.get("evidence").cloned(),
                        payload.get("content_snapshot").cloned(),
                        None,
                        "unilateral",
                        None,
                        None,
                    ).await?;

                    let _ = ctx.emit_public_event(
                        Some(&plugin_name),
                        "ledger.entry_created",
                        json!({
                            "entry_id": entry_id,
                            "action_type": "content_remove",
                            "target_type": content_type,
                        }),
                    ).await;

                    Ok(())
                })
            }),
        );

        // Hook: Log user moderation
        let plugin_name2 = self.metadata().name.to_string();
        system.add_action(
            "moderation.user_action",
            plugin_name2.clone(),
            1,
            Arc::new(move |ctx: HookContext, payload: Value| {
                let plugin_name = plugin_name2.clone();
                Box::pin(async move {
                    let actor_id = ctx.actor_user_id
                        .ok_or_else(|| PluginError::Message("Missing actor_user_id".into()))?;

                    let target_user_id = payload
                        .get("target_user_id")
                        .and_then(|v| v.as_str())
                        .and_then(|s| Uuid::parse_str(s).ok())
                        .ok_or_else(|| PluginError::Message("Missing target_user_id".into()))?;

                    let action = payload
                        .get("action")
                        .and_then(|v| v.as_str())
                        .unwrap_or("user_warn");

                    let action_type = match action {
                        "warn" => ModerationActionType::UserWarn,
                        "mute" => ModerationActionType::UserMute,
                        "unmute" => ModerationActionType::UserUnmute,
                        "suspend" => ModerationActionType::UserSuspend,
                        "unsuspend" => ModerationActionType::UserUnsuspend,
                        "ban" => ModerationActionType::UserBan,
                        "unban" => ModerationActionType::UserUnban,
                        _ => ModerationActionType::UserWarn,
                    };

                    let reason = payload
                        .get("reason")
                        .and_then(|v| v.as_str())
                        .unwrap_or("No reason provided");

                    let actor_role = payload
                        .get("actor_role")
                        .and_then(|v| v.as_str())
                        .unwrap_or("moderator");

                    let duration = payload
                        .get("duration_hours")
                        .and_then(|v| v.as_i64())
                        .map(|d| d as i32);

                    let entry_id = LedgerService::create_entry(
                        &ctx.pool,
                        ctx.community_id,
                        actor_id,
                        actor_role,
                        action_type,
                        "user",
                        target_user_id,
                        reason,
                        payload.get("rule_reference").and_then(|v| v.as_str()),
                        payload.get("evidence").cloned(),
                        None,
                        duration,
                        "unilateral",
                        None,
                        None,
                    ).await?;

                    let _ = ctx.emit_public_event(
                        Some(&plugin_name),
                        "ledger.entry_created",
                        json!({
                            "entry_id": entry_id,
                            "action_type": action,
                            "target_type": "user",
                        }),
                    ).await;

                    Ok(())
                })
            }),
        );

        // Hook: Log proposal moderation
        let plugin_name3 = self.metadata().name.to_string();
        system.add_action(
            "moderation.proposal_action",
            plugin_name3.clone(),
            1,
            Arc::new(move |ctx: HookContext, payload: Value| {
                let plugin_name = plugin_name3.clone();
                Box::pin(async move {
                    let actor_id = ctx.actor_user_id
                        .ok_or_else(|| PluginError::Message("Missing actor_user_id".into()))?;

                    let proposal_id = payload
                        .get("proposal_id")
                        .and_then(|v| v.as_str())
                        .and_then(|s| Uuid::parse_str(s).ok())
                        .ok_or_else(|| PluginError::Message("Missing proposal_id".into()))?;

                    let action = payload
                        .get("action")
                        .and_then(|v| v.as_str())
                        .unwrap_or("close");

                    let action_type = match action {
                        "close" => ModerationActionType::ProposalClose,
                        "reopen" => ModerationActionType::ProposalReopen,
                        "archive" => ModerationActionType::ProposalArchive,
                        _ => ModerationActionType::ProposalClose,
                    };

                    let reason = payload
                        .get("reason")
                        .and_then(|v| v.as_str())
                        .unwrap_or("No reason provided");

                    let actor_role = payload
                        .get("actor_role")
                        .and_then(|v| v.as_str())
                        .unwrap_or("moderator");

                    let decision_type = payload
                        .get("decision_type")
                        .and_then(|v| v.as_str())
                        .unwrap_or("unilateral");

                    let vote_proposal_id = payload
                        .get("vote_proposal_id")
                        .and_then(|v| v.as_str())
                        .and_then(|s| Uuid::parse_str(s).ok());

                    let entry_id = LedgerService::create_entry(
                        &ctx.pool,
                        ctx.community_id,
                        actor_id,
                        actor_role,
                        action_type,
                        "proposal",
                        proposal_id,
                        reason,
                        payload.get("rule_reference").and_then(|v| v.as_str()),
                        payload.get("evidence").cloned(),
                        payload.get("proposal_snapshot").cloned(),
                        None,
                        decision_type,
                        vote_proposal_id,
                        payload.get("vote_result").cloned(),
                    ).await?;

                    let _ = ctx.emit_public_event(
                        Some(&plugin_name),
                        "ledger.entry_created",
                        json!({
                            "entry_id": entry_id,
                            "action_type": action,
                            "target_type": "proposal",
                        }),
                    ).await;

                    Ok(())
                })
            }),
        );
    }
}