use crate::authentication::AuthenticatedUser;
use crate::routes::verify_password;
use crate::session_state::TypedSession;
use crate::templates::{ErrorTemplate, MessageTemplate, UserEditTemplate};
use crate::{
    authentication::Role,
    domain::{PostEntry, UserEntry},
    routes::{AppError, not_found_html},
    startup::AppState,
    templates::{HtmlTemplate, UserTemplate},
};
use anyhow::Context;
use axum::{
    Extension, Form,
    extract::{Path, State},
    response::{IntoResponse, Response},
};
use secrecy::{ExposeSecret, SecretString};
use sqlx::PgPool;
use uuid::Uuid;

pub async fn get_user_edit(
    Path(username): Path<String>,
    Extension(AuthenticatedUser {
        user_id,
        username: session_username,
        ..
    }): Extension<AuthenticatedUser>,
    State(AppState {
        connection_pool, ..
    }): State<AppState>,
) -> Result<Response, AppError> {
    if username != session_username {
        let template = HtmlTemplate(ErrorTemplate::Forbidden);
        return Ok(template.into_response());
    }
    let user = sqlx::query_as!(
        UserEntry,
        r#"
        SELECT user_id, username, role as "role: Role", full_name, bio, member_since
        FROM users
        WHERE user_id = $1
        "#,
        user_id
    )
    .fetch_one(&connection_pool)
    .await
    .context("Could not fetch user in database.")?;
    let template = HtmlTemplate(UserEditTemplate { user });
    Ok(template.into_response())
}

#[derive(serde::Deserialize)]
pub struct EditProfileForm {
    username: String,
    full_name: String,
    bio: String,
}

pub async fn put_user_edit(
    State(AppState {
        connection_pool, ..
    }): State<AppState>,
    session: TypedSession,
    Extension(AuthenticatedUser {
        user_id,
        username: session_username,
        ..
    }): Extension<AuthenticatedUser>,
    Path(username): Path<String>,
    Form(form): Form<EditProfileForm>,
) -> Result<Response, AppError> {
    if username != session_username {
        let template = HtmlTemplate(ErrorTemplate::Forbidden);
        return Ok(template.into_response());
    }
    let updated_username = form.username.trim();
    if updated_username != session_username
        && sqlx::query!(
            "SELECT user_id FROM users WHERE username = $1",
            updated_username
        )
        .fetch_optional(&connection_pool)
        .await
        .context("Could not fetch users table.")?
        .is_some()
    {
        let template = HtmlTemplate(MessageTemplate::error(
            "The username is already taken.".into(),
        ));
        return Ok(template.into_response());
    }
    let updated_full_name = form.full_name.trim();
    let bio = form.bio.trim();
    sqlx::query!(
        "
        UPDATE users
        SET username = $1, full_name = $2, bio = $3
        WHERE user_id = $4
        ",
        updated_username,
        updated_full_name,
        bio,
        user_id
    )
    .execute(&connection_pool)
    .await
    .context("Failed to apply changes.")
    .map_err(AppError::FormError)?;
    session
        .insert_username(updated_username.to_owned())
        .await
        .context("Could not update session username.")?;
    let template = HtmlTemplate(MessageTemplate::success(
        "Your profile has been updated.".into(),
    ));
    Ok(template.into_response())
}

#[tracing::instrument(name = "Get users from database", skip(connection_pool))]
pub async fn get_users(connection_pool: &PgPool) -> Result<Vec<UserEntry>, sqlx::Error> {
    sqlx::query_as!(
        UserEntry,
        r#"
        SELECT user_id, username, role as "role: Role", full_name, bio, member_since
        FROM users
        ORDER BY member_since DESC
        "#
    )
    .fetch_all(connection_pool)
    .await
}

#[derive(Debug, serde::Deserialize)]
pub struct CreateUserForm {
    username: String,
    password: SecretString,
    password_check: SecretString,
    admin: Option<bool>,
}

struct NewUser {
    username: String,
    password_hash: SecretString,
    role: Role,
}

impl TryFrom<CreateUserForm> for NewUser {
    type Error = anyhow::Error;

    fn try_from(value: CreateUserForm) -> Result<Self, Self::Error> {
        if value.username.trim().is_empty() {
            anyhow::bail!("Username cannot be empty.");
        }
        verify_password(value.password.expose_secret())?;
        if value.password.expose_secret() != value.password_check.expose_secret() {
            anyhow::bail!("Password mismatch.");
        }

        let role = match value.admin {
            Some(true) => Role::Admin,
            _ => Role::Writer,
        };
        let password_hash = crate::authentication::compute_pasword_hash(value.password)
            .context("Failed to hash password.")?;
        Ok(Self {
            username: value.username,
            password_hash,
            role,
        })
    }
}

#[tracing::instrument(name = "Creating new user", skip_all, fields(username = %form.username))]
pub async fn create_user(
    State(AppState {
        connection_pool, ..
    }): State<AppState>,
    Form(form): Form<CreateUserForm>,
) -> Result<Response, AppError> {
    let new_user: NewUser = match form.try_into().map_err(|e: anyhow::Error| e.to_string()) {
        Err(e) => {
            let template = HtmlTemplate(MessageTemplate::error(e));
            return Ok(template.into_response());
        }
        Ok(new_user) => new_user,
    };
    insert_user(&connection_pool, new_user)
        .await
        .context("Could not insert user in database.")?;
    let template = HtmlTemplate(MessageTemplate::success(
        "The new user has been created.".into(),
    ));
    Ok(template.into_response())
}

async fn insert_user(connection_pool: &PgPool, new_user: NewUser) -> Result<Uuid, sqlx::Error> {
    let user_id = Uuid::new_v4();
    sqlx::query!(
        r#"
        INSERT INTO users (user_id, username, password_hash, role)
        VALUES ($1, $2, $3, $4)
        "#,
        user_id,
        new_user.username,
        new_user.password_hash.expose_secret(),
        new_user.role as _
    )
    .execute(connection_pool)
    .await?;
    Ok(user_id)
}

#[derive(serde::Deserialize)]
pub struct SubscriberPathParams {
    pub user_id: Uuid,
}

#[tracing::instrument(name = "Delete user from database", skip(connection_pool))]
pub async fn delete_user(
    State(AppState {
        connection_pool, ..
    }): State<AppState>,
    Path(SubscriberPathParams { user_id }): Path<SubscriberPathParams>,
) -> Result<Response, AppError> {
    let result = sqlx::query!("DELETE FROM users WHERE user_id = $1", user_id)
        .execute(&connection_pool)
        .await
        .context("Failed to delete user from database.")?;
    let template = if result.rows_affected() == 0 {
        HtmlTemplate(MessageTemplate::error(
            "The user could not be deleted.".into(),
        ))
    } else {
        HtmlTemplate(MessageTemplate::success(
            "The user has been deleted.".into(),
        ))
    };
    Ok(template.into_response())
}

#[tracing::instrument(name = "Fetching user data", skip(connection_pool, session))]
pub async fn user_profile(
    session: TypedSession,
    State(AppState {
        connection_pool, ..
    }): State<AppState>,
    Path(username): Path<String>,
) -> Result<Response, AppError> {
    match fetch_user_data(&connection_pool, &username)
        .await
        .context("Failed to fetch user data.")?
    {
        Some(user) => {
            let posts = fetch_user_posts(&connection_pool, &user.user_id)
                .await
                .context("Could not fetch user posts.")?;
            let session_username = session
                .get_username()
                .await
                .context("Could not fetch session username.")?;
            let template = HtmlTemplate(UserTemplate {
                user,
                session_username,
                posts,
            });
            Ok(template.into_response())
        }
        None => {
            tracing::error!(username = %username, "user not found");
            Ok(not_found_html().into_response())
        }
    }
}

#[tracing::instrument(name = "Fetching user profile", skip_all)]
async fn fetch_user_data(
    connection_pool: &PgPool,
    username: &str,
) -> Result<Option<UserEntry>, sqlx::Error> {
    sqlx::query_as!(
        UserEntry,
        r#"
        SELECT user_id, username, full_name, role as "role: Role", member_since, bio
        FROM users
        WHERE username = $1
        "#,
        username
    )
    .fetch_optional(connection_pool)
    .await
}

#[tracing::instrument(name = "Fetching user posts", skip_all)]
async fn fetch_user_posts(
    connection_pool: &PgPool,
    user_id: &Uuid,
) -> Result<Vec<PostEntry>, sqlx::Error> {
    sqlx::query_as!(
        PostEntry,
        r#"
        SELECT u.username as author, p.post_id, p.title, p.content, p.published_at
        FROM posts p
        INNER JOIN users u ON p.author_id = u.user_id
        WHERE p.author_id = $1
        ORDER BY p.published_at DESC
        "#,
        user_id
    )
    .fetch_all(connection_pool)
    .await
}