feat: implement user authentication system with admin dashboard

src/data/users.rs

@@ -0,0 +1,86 @@
+//! Database query functions for users.
+
+use anyhow::Context;
+use sqlx::PgPool;
+
+use super::models::User;
+use crate::error::Result;
+
+/// Insert a new user or update username/avatar on conflict.
+pub async fn upsert_user(
+    pool: &PgPool,
+    discord_id: i64,
+    username: &str,
+    avatar_hash: Option<&str>,
+) -> Result<User> {
+    sqlx::query_as::<_, User>(
+        r#"
+        INSERT INTO users (discord_id, discord_username, discord_avatar_hash)
+        VALUES ($1, $2, $3)
+        ON CONFLICT (discord_id) DO UPDATE
+            SET discord_username = EXCLUDED.discord_username,
+                discord_avatar_hash = EXCLUDED.discord_avatar_hash,
+                updated_at = now()
+        RETURNING *
+        "#,
+    )
+    .bind(discord_id)
+    .bind(username)
+    .bind(avatar_hash)
+    .fetch_one(pool)
+    .await
+    .context("failed to upsert user")
+}
+
+/// Fetch a user by Discord ID.
+pub async fn get_user(pool: &PgPool, discord_id: i64) -> Result<Option<User>> {
+    sqlx::query_as::<_, User>("SELECT * FROM users WHERE discord_id = $1")
+        .bind(discord_id)
+        .fetch_optional(pool)
+        .await
+        .context("failed to get user")
+}
+
+/// List all users ordered by creation date (newest first).
+pub async fn list_users(pool: &PgPool) -> Result<Vec<User>> {
+    sqlx::query_as::<_, User>("SELECT * FROM users ORDER BY created_at DESC")
+        .fetch_all(pool)
+        .await
+        .context("failed to list users")
+}
+
+/// Set the admin flag for a user, returning the updated user if found.
+pub async fn set_admin(pool: &PgPool, discord_id: i64, is_admin: bool) -> Result<Option<User>> {
+    sqlx::query_as::<_, User>(
+        r#"
+        UPDATE users
+        SET is_admin = $2, updated_at = now()
+        WHERE discord_id = $1
+        RETURNING *
+        "#,
+    )
+    .bind(discord_id)
+    .bind(is_admin)
+    .fetch_optional(pool)
+    .await
+    .context("failed to set admin status")
+}
+
+/// Ensure a seed admin exists. Upserts with `is_admin = true` and a placeholder
+/// username that will be replaced on first OAuth login.
+pub async fn ensure_seed_admin(pool: &PgPool, discord_id: i64) -> Result<User> {
+    sqlx::query_as::<_, User>(
+        r#"
+        INSERT INTO users (discord_id, discord_username, is_admin)
+        VALUES ($1, 'seed-admin', true)
+        ON CONFLICT (discord_id) DO UPDATE
+            SET is_admin = true,
+                updated_at = now()
+        RETURNING *
+        "#,
+    )
+    .bind(discord_id)
+    .fetch_one(pool)
+    .await
+    .context("failed to ensure seed admin")
+}