//! Admin queue for monthly mail allowance increases.
//!
//! The operator half of `db::mail_caps`. A creator asks with a number and a
//! reason; this is where the ask lands and where granting it writes the
//! per-account override. Granting and writing the override are one transaction
//! in the db layer, because a granted request whose override never landed is a
//! creator still being refused.

use axum::{
    Form,
    extract::{Path, State},
    response::{IntoResponse, Response},
};
use serde::Deserialize;
use sqlx::PgPool;
use tower_sessions::Session;

use crate::{
    auth::AdminUser,
    db,
    error::Result,
    helpers::get_csrf_token,
    templates::{AdminMailCapEntriesTemplate, AdminMailCapsTemplate},
    types::AdminMailCapRow,
};

#[derive(Debug, Deserialize)]
pub(super) struct GrantForm {
    /// What the operator is granting, which need not be what was asked for.
    pub granted_cap: i32,
}

/// The pending queue, oldest first.
#[tracing::instrument(skip_all, name = "admin::admin_mail_caps")]
pub(super) async fn admin_mail_caps(
    State(db): State<PgPool>,
    session: Session,
    AdminUser(admin): AdminUser,
) -> Result<impl IntoResponse> {
    Ok(AdminMailCapsTemplate {
        csrf_token: get_csrf_token(&session).await,
        session_user: Some(admin),
        entries: rows(&db).await?,
        admin_active_page: "mail-caps",
    })
}

/// Grant a request, at the operator's number rather than the creator's.
#[tracing::instrument(skip_all, name = "admin::admin_mail_cap_grant")]
pub(super) async fn admin_mail_cap_grant(
    State(db): State<PgPool>,
    session: Session,
    AdminUser(admin): AdminUser,
    Path(id): Path<uuid::Uuid>,
    Form(form): Form<GrantForm>,
) -> Result<Response> {
    if form.granted_cap > 0 {
        match db::mail_caps::grant_request(&db, id, form.granted_cap, admin.id).await? {
            Some(user_id) => tracing::info!(
                request_id = %id, user_id = %user_id, granted_cap = form.granted_cap,
                "granted a monthly mail allowance increase"
            ),
            // Already decided by another operator, or gone. The queue below
            // re-renders without it, which is the answer.
            None => tracing::info!(request_id = %id, "mail cap request was already decided"),
        }
    }

    Ok(AdminMailCapEntriesTemplate {
        csrf_token: get_csrf_token(&session).await,
        entries: rows(&db).await?,
    }
    .into_response())
}

/// Deny a request. The tier default keeps applying.
#[tracing::instrument(skip_all, name = "admin::admin_mail_cap_deny")]
pub(super) async fn admin_mail_cap_deny(
    State(db): State<PgPool>,
    session: Session,
    AdminUser(admin): AdminUser,
    Path(id): Path<uuid::Uuid>,
) -> Result<Response> {
    if let Some(user_id) = db::mail_caps::deny_request(&db, id, admin.id).await? {
        tracing::info!(request_id = %id, user_id = %user_id, "denied a monthly mail allowance increase");
    }

    Ok(AdminMailCapEntriesTemplate {
        csrf_token: get_csrf_token(&session).await,
        entries: rows(&db).await?,
    }
    .into_response())
}

/// The queue as the table renders it: the request, plus who asked and what they
/// have today, since a number means nothing without the one it would replace.
async fn rows(db: &PgPool) -> Result<Vec<AdminMailCapRow>> {
    let requests = db::mail_caps::pending_requests(db).await?;
    let mut entries = Vec::with_capacity(requests.len());
    for request in requests {
        let (username, email) = match db::users::get_user_by_id(db, request.user_id).await? {
            Some(user) => (user.username.to_string(), user.email.to_string()),
            // A request whose account went away between the query and this
            // read. Show the row rather than dropping it silently; an operator
            // deciding it is harmless and the alternative is a queue that
            // quietly shrinks.
            None => ("(deleted account)".to_string(), String::new()),
        };
        let current_cap = db::mail_caps::effective_cap(db, request.user_id).await?;
        entries.push(AdminMailCapRow {
            id: request.id,
            username,
            email,
            current_cap,
            requested_cap: request.requested_cap,
            reason: request.reason,
            created_at: request.created_at.format("%b %d, %Y %H:%M").to_string(),
        });
    }
    Ok(entries)
}