use crate::AppService;
use crate::error::AppError;
use chrono::Utc;
use models::issues::{ReactionType, issue, issue_comment, issue_comment_reaction, issue_reaction};
use models::projects::project_members;
use sea_orm::*;
use serde::{Deserialize, Serialize};
use session::Session;
use std::str::FromStr;
use utoipa::ToSchema;
use uuid::Uuid;

#[derive(Debug, Clone, Deserialize, ToSchema)]
pub struct ReactionAddRequest {
    pub reaction: String,
}

#[derive(Debug, Clone, Serialize, ToSchema)]
pub struct ReactionResponse {
    pub user: Uuid,
    pub reaction: String,
    pub created_at: chrono::DateTime<Utc>,
}

#[derive(Debug, Clone, Serialize, ToSchema)]
pub struct ReactionSummary {
    pub reaction: String,
    pub count: i64,
    pub users: Vec<Uuid>,
}

#[derive(Debug, Clone, Serialize, ToSchema)]
pub struct ReactionListResponse {
    pub reactions: Vec<ReactionSummary>,
}

impl AppService {
    /// List reactions summary on an issue.
    pub async fn issue_reaction_list(
        &self,
        project_name: String,
        issue_number: i64,
        ctx: &Session,
    ) -> Result<ReactionListResponse, AppError> {
        let project = self.utils_find_project_by_name(project_name).await?;
        if let Some(uid) = ctx.user() {
            self.check_project_access(project.id, uid).await?;
        }

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        let reactions = issue_reaction::Entity::find()
            .filter(issue_reaction::Column::Issue.eq(issue.id))
            .all(&self.db)
            .await?;

        let summaries = self.aggregate_reactions(reactions);
        Ok(ReactionListResponse {
            reactions: summaries,
        })
    }

    /// Add a reaction to an issue.
    pub async fn issue_reaction_add(
        &self,
        project_name: String,
        issue_number: i64,
        request: ReactionAddRequest,
        ctx: &Session,
    ) -> Result<ReactionResponse, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let project = self.utils_find_project_by_name(project_name).await?;

        let _member = project_members::Entity::find()
            .filter(project_members::Column::Project.eq(project.id))
            .filter(project_members::Column::User.eq(user_uid))
            .one(&self.db)
            .await?
            .ok_or(AppError::NoPower)?;

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        let _ = ReactionType::from_str(&request.reaction)
            .map_err(|_| AppError::BadRequest("Unknown reaction type".to_string()))?;

        let existing = issue_reaction::Entity::find()
            .filter(issue_reaction::Column::Issue.eq(issue.id))
            .filter(issue_reaction::Column::User.eq(user_uid))
            .filter(issue_reaction::Column::Reaction.eq(&request.reaction))
            .one(&self.db)
            .await?;

        if let Some(e) = existing {
            return Ok(ReactionResponse {
                user: e.user,
                reaction: e.reaction,
                created_at: e.created_at,
            });
        }

        let now = Utc::now();
        let active = issue_reaction::ActiveModel {
            issue: Set(issue.id),
            user: Set(user_uid),
            reaction: Set(request.reaction),
            created_at: Set(now),
            ..Default::default()
        };
        let model = active.insert(&self.db).await?;

        Ok(ReactionResponse {
            user: model.user,
            reaction: model.reaction,
            created_at: model.created_at,
        })
    }

    pub async fn issue_reaction_remove(
        &self,
        project_name: String,
        issue_number: i64,
        reaction: String,
        ctx: &Session,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let project = self.utils_find_project_by_name(project_name).await?;

        let _member = project_members::Entity::find()
            .filter(project_members::Column::Project.eq(project.id))
            .filter(project_members::Column::User.eq(user_uid))
            .one(&self.db)
            .await?
            .ok_or(AppError::NoPower)?;

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        issue_reaction::Entity::delete_many()
            .filter(issue_reaction::Column::Issue.eq(issue.id))
            .filter(issue_reaction::Column::User.eq(user_uid))
            .filter(issue_reaction::Column::Reaction.eq(reaction))
            .exec(&self.db)
            .await?;

        Ok(())
    }

    /// List reactions on a comment.
    pub async fn issue_comment_reaction_list(
        &self,
        project_name: String,
        issue_number: i64,
        comment_id: i64,
        ctx: &Session,
    ) -> Result<ReactionListResponse, AppError> {
        let project = self.utils_find_project_by_name(project_name).await?;
        if let Some(uid) = ctx.user() {
            self.check_project_access(project.id, uid).await?;
        }

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        let comment = issue_comment::Entity::find_by_id(comment_id)
            .filter(issue_comment::Column::Issue.eq(issue.id))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Comment not found".to_string()))?;

        let reactions = issue_comment_reaction::Entity::find()
            .filter(issue_comment_reaction::Column::Comment.eq(comment.id))
            .all(&self.db)
            .await?;

        let summaries = self.aggregate_comment_reactions(reactions);
        Ok(ReactionListResponse {
            reactions: summaries,
        })
    }

    /// Add a reaction to a comment.
    pub async fn issue_comment_reaction_add(
        &self,
        project_name: String,
        issue_number: i64,
        comment_id: i64,
        request: ReactionAddRequest,
        ctx: &Session,
    ) -> Result<ReactionResponse, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let project = self.utils_find_project_by_name(project_name).await?;

        let _member = project_members::Entity::find()
            .filter(project_members::Column::Project.eq(project.id))
            .filter(project_members::Column::User.eq(user_uid))
            .one(&self.db)
            .await?
            .ok_or(AppError::NoPower)?;

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        let comment = issue_comment::Entity::find_by_id(comment_id)
            .filter(issue_comment::Column::Issue.eq(issue.id))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Comment not found".to_string()))?;

        let _ = ReactionType::from_str(&request.reaction)
            .map_err(|_| AppError::BadRequest("Unknown reaction type".to_string()))?;

        let existing = issue_comment_reaction::Entity::find()
            .filter(issue_comment_reaction::Column::Comment.eq(comment.id))
            .filter(issue_comment_reaction::Column::User.eq(user_uid))
            .filter(issue_comment_reaction::Column::Reaction.eq(&request.reaction))
            .one(&self.db)
            .await?;

        if let Some(e) = existing {
            return Ok(ReactionResponse {
                user: e.user,
                reaction: e.reaction,
                created_at: e.created_at,
            });
        }

        let now = Utc::now();
        let active = issue_comment_reaction::ActiveModel {
            comment: Set(comment.id),
            user: Set(user_uid),
            reaction: Set(request.reaction),
            created_at: Set(now),
            ..Default::default()
        };
        let model = active.insert(&self.db).await?;

        Ok(ReactionResponse {
            user: model.user,
            reaction: model.reaction,
            created_at: model.created_at,
        })
    }

    pub async fn issue_comment_reaction_remove(
        &self,
        project_name: String,
        issue_number: i64,
        comment_id: i64,
        reaction: String,
        ctx: &Session,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let project = self.utils_find_project_by_name(project_name).await?;

        let _member = project_members::Entity::find()
            .filter(project_members::Column::Project.eq(project.id))
            .filter(project_members::Column::User.eq(user_uid))
            .one(&self.db)
            .await?
            .ok_or(AppError::NoPower)?;

        let issue = issue::Entity::find()
            .filter(issue::Column::Project.eq(project.id))
            .filter(issue::Column::Number.eq(issue_number))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Issue not found".to_string()))?;

        let comment = issue_comment::Entity::find_by_id(comment_id)
            .filter(issue_comment::Column::Issue.eq(issue.id))
            .one(&self.db)
            .await?
            .ok_or(AppError::NotFound("Comment not found".to_string()))?;

        issue_comment_reaction::Entity::delete_many()
            .filter(issue_comment_reaction::Column::Comment.eq(comment.id))
            .filter(issue_comment_reaction::Column::User.eq(user_uid))
            .filter(issue_comment_reaction::Column::Reaction.eq(reaction))
            .exec(&self.db)
            .await?;

        Ok(())
    }

    fn aggregate_reactions(&self, reactions: Vec<issue_reaction::Model>) -> Vec<ReactionSummary> {
        use std::collections::HashMap;
        let mut map: HashMap<String, (i64, Vec<Uuid>)> = HashMap::new();
        for r in reactions {
            let entry = map.entry(r.reaction.clone()).or_insert_with(|| (0, vec![]));
            entry.0 += 1;
            entry.1.push(r.user);
        }
        map.into_iter()
            .map(|(reaction, (count, users))| ReactionSummary {
                reaction,
                count,
                users,
            })
            .collect()
    }

    fn aggregate_comment_reactions(
        &self,
        reactions: Vec<issue_comment_reaction::Model>,
    ) -> Vec<ReactionSummary> {
        use std::collections::HashMap;
        let mut map: HashMap<String, (i64, Vec<Uuid>)> = HashMap::new();
        for r in reactions {
            let entry = map.entry(r.reaction.clone()).or_insert_with(|| (0, vec![]));
            entry.0 += 1;
            entry.1.push(r.user);
        }
        map.into_iter()
            .map(|(reaction, (count, users))| ReactionSummary {
                reaction,
                count,
                users,
            })
            .collect()
    }
}