use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::error::AppError;
use crate::models::common::Role;
use crate::models::repos::RepoInvitation;
use crate::pb::email::{EmailAddress, SendEmailRequest};
use crate::service::RepoService;
use crate::session::Session;

use super::util::{clamp_limit_offset, ensure_affected, role_level};

#[derive(Deserialize, Serialize, Clone, Debug, utoipa::ToSchema)]
pub struct CreateRepoInvitationParams {
    pub email: String,
    pub role: Option<String>,
}

#[derive(Serialize, Clone, Debug)]
pub struct CreateRepoInvitationResponse {
    pub invitation: RepoInvitation,
}

impl RepoService {
    pub async fn repo_invitations(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<RepoInvitation>, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;
        self.ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;
        let (limit, offset) = clamp_limit_offset(limit, offset);
        sqlx::query_as::<_, RepoInvitation>(
            "SELECT id, repo_id, email, role, token_hash, invited_by, accepted_by, accepted_at, revoked_at, expires_at, created_at FROM repo_invitation \
             WHERE repo_id = $1 AND revoked_at IS NULL AND accepted_at IS NULL \
             AND expires_at > NOW() ORDER BY created_at DESC LIMIT $2 OFFSET $3",
        )
        .bind(repo_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)
    }

    pub async fn repo_create_invitation(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        params: CreateRepoInvitationParams,
    ) -> Result<CreateRepoInvitationResponse, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;
        let actor_role = self
            .ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;

        let email = params.email.trim().to_lowercase();
        if email.is_empty() {
            return Err(AppError::BadRequest("email is required".into()));
        }

        let existing = sqlx::query_scalar::<_, bool>(
            "SELECT EXISTS(SELECT 1 FROM repo_invitation \
             WHERE repo_id = $1 AND lower(email) = lower($2) \
             AND revoked_at IS NULL AND accepted_at IS NULL AND expires_at > NOW())",
        )
        .bind(repo_id)
        .bind(&email)
        .fetch_one(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?;

        if existing {
            return Err(AppError::BadRequest(
                "invitation already exists for this email".into(),
            ));
        }

        let role = params
            .role
            .as_deref()
            .and_then(|r| r.parse::<Role>().ok())
            .unwrap_or(Role::Member);

        if role == Role::Owner || role == Role::Unknown {
            return Err(AppError::BadRequest("invalid role for invitation".into()));
        }

        // Non-owner admins cannot invite with roles equal to or higher than their own
        if actor_role != Role::Owner && role_level(role) >= role_level(actor_role) {
            return Err(AppError::BadRequest(
                "cannot invite with role equal to or higher than your own".into(),
            ));
        }

        let token = generate_repo_invitation_token();
        let token_hash = sha256_hex(token.as_bytes());
        let now = chrono::Utc::now();
        let expires_at = now + chrono::Duration::days(7);

        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query("SET LOCAL app.current_user_id = $1")
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let invitation = sqlx::query_as::<_, RepoInvitation>(
            "INSERT INTO repo_invitation (id, repo_id, email, role, token_hash, invited_by, expires_at, created_at) \
             VALUES ($1, $2, $3, $4, $5, $6, $7, $8) \
             RETURNING id, repo_id, email, role, token_hash, invited_by, accepted_by, accepted_at, revoked_at, expires_at, created_at",
        )
        .bind(Uuid::now_v7())
        .bind(repo_id)
        .bind(&email)
        .bind(role.to_string())
        .bind(&token_hash)
        .bind(user_uid)
        .bind(expires_at)
        .bind(now)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;

        let domain = self.ctx.config.main_domain()?;
        let invite_link = format!("{}/repo/invitations/accept?token={}", domain, token);
        let mut mail = self
            .ctx
            .registry
            .get_email_client()
            .ok_or(AppError::Config("mail service not available".into()))?;
        mail.send_email(tonic::Request::new(SendEmailRequest {
            to: vec![EmailAddress {
                email: email.clone(),
                name: String::new(),
            }],
            subject: format!("You're invited to join repo {}", repo.name),
            text_body: format!(
                "You've been invited to join repository '{}'.\n\nAccept the invitation here:\n\n{}\n\nThis invitation expires in 7 days.",
                repo.name, invite_link
            ),
            ..Default::default()
        }))
        .await
        .map_err(|e| AppError::InternalServerError(e.to_string()))?;

        tracing::info!(email = %email, invitation_id = %invitation.id, repo_id = %repo_id, "Repo invitation created");
        Ok(CreateRepoInvitationResponse { invitation })
    }

    pub async fn repo_revoke_invitation(
        &self,
        ctx: &Session,
        wk_name: &str,
        repo_name: &str,
        invitation_id: Uuid,
    ) -> Result<(), AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let repo = self.resolve_repo(wk_name, repo_name).await?;
        let repo_id = repo.id;
        self.ensure_repo_role_at_least(user_uid, &repo, Role::Admin)
            .await?;

        let now = chrono::Utc::now();
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query("SET LOCAL app.current_user_id = $1")
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let result = sqlx::query(
            "UPDATE repo_invitation SET revoked_at = $1 WHERE id = $2 AND repo_id = $3 \
             AND revoked_at IS NULL AND accepted_at IS NULL",
        )
        .bind(now)
        .bind(invitation_id)
        .bind(repo_id)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;
        ensure_affected(
            result.rows_affected(),
            "invitation not found or already used",
        )?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;
        Ok(())
    }

    pub async fn repo_accept_invitation(
        &self,
        ctx: &Session,
        token: &str,
    ) -> Result<RepoInvitation, AppError> {
        let user_uid = ctx.user().ok_or(AppError::Unauthorized)?;
        let token_hash = sha256_hex(token.as_bytes());
        let now = chrono::Utc::now();

        let invitation = sqlx::query_as::<_, RepoInvitation>(
            "SELECT id, repo_id, email, role, token_hash, invited_by, accepted_by, accepted_at, revoked_at, expires_at, created_at FROM repo_invitation \
             WHERE token_hash = $1 AND revoked_at IS NULL AND accepted_at IS NULL AND expires_at > NOW()",
        )
        .bind(&token_hash)
        .fetch_optional(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?
        .ok_or(AppError::BadRequest("invalid or expired invitation".into()))?;

        let already_member = sqlx::query_scalar::<_, bool>(
            "SELECT EXISTS(SELECT 1 FROM repo_member WHERE repo_id = $1 AND user_id = $2)",
        )
        .bind(invitation.repo_id)
        .bind(user_uid)
        .fetch_one(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?;

        if already_member {
            return Err(AppError::BadRequest("already a member of this repo".into()));
        }

        let user_email: Option<String> = sqlx::query_scalar(
            "SELECT email FROM user_mail WHERE user_id = $1 AND is_verified = true LIMIT 1",
        )
        .bind(user_uid)
        .fetch_optional(self.ctx.db.reader())
        .await
        .map_err(AppError::Database)?;
        if user_email
            .as_deref()
            .map(|e| e.trim().eq_ignore_ascii_case(&invitation.email))
            != Some(true)
        {
            return Err(AppError::Unauthorized);
        }

        let repo = self.find_repo_by_id(invitation.repo_id).await?;
        let role_str = invitation.role.to_string();
        let mut txn = self
            .ctx
            .db
            .writer()
            .begin()
            .await
            .map_err(|_| AppError::TxnError)?;
        sqlx::query("SET LOCAL app.current_user_id = $1")
            .bind(user_uid)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;

        let workspace_member_result = sqlx::query(
            "INSERT INTO workspace_member (id, workspace_id, user_id, role, status, joined_at, created_at, updated_at) \
             VALUES ($1, $2, $3, 'member', 'active', $4, $4, $4) ON CONFLICT (workspace_id, user_id) DO NOTHING",
        )
        .bind(Uuid::now_v7())
        .bind(repo.workspace_id)
        .bind(user_uid)
        .bind(now)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        if workspace_member_result.rows_affected() > 0 {
            sqlx::query(
                "UPDATE workspace_stats SET members_count = members_count + 1, updated_at = $1 WHERE workspace_id = $2",
            )
            .bind(now)
            .bind(repo.workspace_id)
            .execute(&mut *txn)
            .await
            .map_err(AppError::Database)?;
        }

        let result = sqlx::query_as::<_, RepoInvitation>(
            "UPDATE repo_invitation SET accepted_by = $1, accepted_at = $2 \
             WHERE id = $3 AND revoked_at IS NULL AND accepted_at IS NULL \
             RETURNING id, repo_id, email, role, token_hash, invited_by, accepted_by, accepted_at, revoked_at, expires_at, created_at",
        )
        .bind(user_uid)
        .bind(now)
        .bind(invitation.id)
        .fetch_one(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        sqlx::query(
            "INSERT INTO repo_member (id, repo_id, user_id, role, status, invited_by, joined_at, created_at, updated_at) \
             VALUES ($1, $2, $3, $4, 'active', $5, $6, $6, $6) \
             ON CONFLICT (repo_id, user_id) DO NOTHING",
        )
        .bind(Uuid::now_v7())
        .bind(invitation.repo_id)
        .bind(user_uid)
        .bind(&role_str)
        .bind(invitation.invited_by)
        .bind(now)
        .execute(&mut *txn)
        .await
        .map_err(AppError::Database)?;

        txn.commit().await.map_err(|_| AppError::TxnError)?;
        Ok(result)
    }
}

fn sha256_hex(data: &[u8]) -> String {
    use sha2::Digest;
    sha2::Sha256::digest(data)
        .iter()
        .map(|b| format!("{b:02x}"))
        .collect()
}

fn generate_repo_invitation_token() -> String {
    (0..64)
        .map(|_| format!("{:02x}", rand::random::<u8>()))
        .collect()
}