use gloo_net::http::Request;
use serde::{Deserialize, Serialize};
use wasm_bindgen_futures::spawn_local;
use yew::prelude::*;
use yew_router::prelude::*;

// #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
// pub struct User {
//     pub id: i16,
//     pub last_name: String,
//     pub first_name: String,
//     pub username: String,
//     pub is_admin: bool,
//     pub pwd: String,
// }

/// Data transfer object (DTO) for creating a new user.
///
/// This struct defines the payload sent to the backend when an administrator
/// registers a new user. It includes all necessary information for user creation.
///
/// # Fields
/// - `first_name`: The first name of the user.
/// - `last_name`: The last name of the user.
/// - `username`: The unique username for the user's login.
/// - `is_admin`: A boolean indicating whether the new user should have administrator privileges.
/// - `pwd`: The password for the user's account. This will be hashed on the backend.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct UserCreateScheme {
    pub first_name: String,
    pub last_name: String,
    pub username: String,
    pub is_admin: bool,
    pub pwd: String,
}

/// Data transfer object (DTO) for user login credentials.
///
/// This struct defines the payload sent to the backend when a user attempts to log in.
///
/// # Fields
/// - `username`: The username provided by the user.
/// - `pwd`: The password provided by the user.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct LoginScheme {
    pub username: String,
    pub pwd: String,
}

/// Data transfer object (DTO) for updating an existing user's information.
///
/// This struct is used to send updated user details, including an optional new password,
/// to the backend for an existing user.
///
/// # Fields
/// - `id`: The unique identifier of the user to be updated.
/// - `first_name`: The updated first name of the user.
/// - `last_name`: The updated last name of the user.
/// - `username`: The updated username for the user.
/// - `make_admin`: A boolean indicating whether to grant/revoke administrator privileges.
/// - `new_pwd`: An optional new password for the user. If empty, the password remains unchanged.
#[derive(Deserialize, Serialize, Debug)]
pub struct UserUpdateScheme {
    pub id: i16,
    pub first_name: String,
    pub last_name: String,
    pub username: String,
    pub make_admin: bool,
    pub new_pwd: String,
}

/// Represents a user entity with sensitive information filtered out.
///
/// This struct is used for displaying user information in contexts where
/// the password hash or other sensitive details are not needed or should not be exposed.
/// It's typically used for listing users or displaying user profiles.
///
/// # Fields
/// - `id`: The unique identifier of the user.
/// - `first_name`: The first name of the user.
/// - `last_name`: The last name of the user.
/// - `username`: The unique username of the user.
/// - `is_admin`: A boolean indicating if the user has administrator privileges.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct FilteredUser {
    pub id: i16,
    pub first_name: String,
    pub last_name: String,
    pub username: String,
    pub is_admin: bool,
}

/// Properties for components that display or interact with a single user.
///
/// This struct is used to pass the ID of a specific user to components
/// that need to fetch, display, or modify their details.
///
/// # Fields
/// - `id`: The unique identifier of the user to be displayed or acted upon.
#[derive(Properties, PartialEq)]
pub struct UserProps {
    pub id: i16,
}

#[derive(Deserialize, Debug)]
struct ApiError {
    message: String,
    _status: String,
}

/// A component providing a form for registering new users.
///
/// This component allows an administrator to create new user accounts by providing
/// their first name, last name, username, password, and specifying if they should
/// be an administrator. The component handles form input, validation (basic),
/// and interaction with the backend `/api/register` endpoint.
///
/// # State
/// Uses `use_state` hooks to manage:
/// - `first_name`, `last_name`, `username`, `pwd`: Values of the form input fields.
/// - `is_admin`: Boolean state for the admin checkbox.
/// - `status`: To display messages about registration success or errors.
///
/// # Form Submission
/// - Prevents default form submission behavior.
/// - Constructs a `UserCreateScheme` payload from the form data.
/// - Sends a POST request to `/api/register`.
/// - Updates the `status` state based on the API response.
///
/// # Example
/// ```rust
/// html! {
///     <Register />
/// }
/// ```
#[component(Register)]
pub fn register_component() -> Html {
    let first_name = use_state(|| "".to_string());
    let last_name = use_state(|| "".to_string());
    let username = use_state(|| "".to_string());
    let is_admin = use_state(|| false);
    let pwd = use_state(|| "".to_string());
    let status = use_state(|| None::<String>);

    let onsubmit = {
        let first_name = first_name.clone();
        let last_name = last_name.clone();
        let username = username.clone();
        let is_admin = is_admin.clone();
        let pwd = pwd.clone();
        let status = status.clone();

        Callback::from(move |e: SubmitEvent| {
            e.prevent_default();
            let first_name = (*first_name).clone();
            let last_name = (*last_name).clone();
            let username = (*username).clone();
            let is_admin = *is_admin;
            let pwd = (*pwd).clone();
            let status = status.clone();

            spawn_local(async move {
                let payload = UserCreateScheme {
                    first_name,
                    last_name,
                    username,
                    is_admin,
                    pwd,
                };

                let request = Request::post("/api/register")
                    .json(&payload)
                    .expect("Error building request");

                match request.send().await {
                    Ok(response) if response.status() == 200 => status.set(Some("Success".into())),
                    Ok(response) => status.set(Some(format!("Error: {}", response.status()))),
                    Err(err) => status.set(Some(format!("Network error: {}", err))),
                }
            });
        })
    };

    let fn_change = {
        let first_name = first_name.clone();
        Callback::from(move |e: InputEvent| {
            let input: web_sys::HtmlInputElement = e.target_unchecked_into();
            first_name.set(input.value());
        })
    };

    let ln_change = {
        let last_name = last_name.clone();
        Callback::from(move |e: InputEvent| {
            let input: web_sys::HtmlInputElement = e.target_unchecked_into();
            last_name.set(input.value());
        })
    };

    let un_change = {
        let username = username.clone();
        Callback::from(move |e: InputEvent| {
            let input: web_sys::HtmlInputElement = e.target_unchecked_into();
            username.set(input.value());
        })
    };

    let admin_change = {
        let is_admin = is_admin.clone();
        Callback::from(move |e: Event| {
            let input: web_sys::HtmlInputElement = e.target_unchecked_into();
            is_admin.set(input.checked());
        })
    };

    let pwd_change = {
        let pwd = pwd.clone();
        Callback::from(move |e: InputEvent| {
            let input: web_sys::HtmlInputElement = e.target_unchecked_into();
            pwd.set(input.value());
        })
    };

    html! {
        <form {onsubmit}>
            <label>{ "Vorname:" }
                <input type="text" value={(*first_name).clone()} oninput={fn_change}/>
            </label>
            <label>{ "Nachname:" }
                <input type="text" value={(*last_name).clone()} oninput={ln_change}/>
            </label>
            <label>{ "Benutzername:" }
                <input type="text" value={(*username).clone()} oninput={un_change}/>
            </label>
            <label>{ "Admin:" }
                <input type="checkbox" checked={*is_admin} onchange={admin_change}/>
            </label>
            <label>{ "Password:" }
                <input type="password" value={(*pwd).clone()} oninput={pwd_change}/>
            </label>
            <button type="submit">{ "Bestätigen" }</button>
        </form>
    }
}

/// A component providing a form for user login.
///
/// This component handles user authentication by collecting a username and password,
/// then sending these credentials to the backend `/api/login` endpoint. It manages
/// UI states for loading, errors, and success, and redirects to the home page on successful login.
///
/// # State
/// Uses `use_state` hooks to manage:
/// - `username`, `pwd`: Values of the login form input fields.
/// - `loading`: A boolean to indicate if the login process is ongoing.
/// - `error`: A string to display any login error messages.
/// - `success`: A boolean to indicate if login was successful.
///
/// # Form Submission
/// - Prevents default form submission behavior.
/// - Constructs a `LoginScheme` payload from the input fields.
/// - Sends a POST request to `/api/login`.
/// - On successful response (HTTP 200), sets `success` to true and redirects to `crate::Route::Home`.
/// - On error, updates the `error` state with the appropriate message.
///
/// # Example
/// ```rust
/// html! {
///     <Login />
/// }
/// ```
#[component(Login)]
pub fn login_component() -> Html {
    let username = use_state(|| "".to_string());
    let pwd = use_state(|| "".to_string());
    let loading = use_state(|| false);
    let error = use_state(|| String::new());
    let success = use_state(|| false);
    let navigator = use_navigator().unwrap();

    let onsubmit = {
        let username = username.clone();
        let pwd = pwd.clone();
        let loading = loading.clone();
        let error = error.clone();
        let success = success.clone();
        let navigator = navigator.clone();

        Callback::from(move |e: SubmitEvent| {
            e.prevent_default();
            let username = (*username).clone();
            let pwd = (*pwd).clone();
            let loading = loading.clone();
            let error = error.clone();
            let success = success.clone();
            let navigator = navigator.clone();

            loading.set(true);
            error.set(String::new());
            success.set(false);

            spawn_local(async move {
                let payload = LoginScheme { username, pwd };

                let response = Request::post("/api/login")
                    .header("Content-Type", "application/json")
                    .credentials(web_sys::RequestCredentials::Include)
                    .json(&payload)
                    .unwrap()
                    .send()
                    .await;

                loading.set(false);

                match response {
                    Ok(r) if r.status() == 200 => {
                        success.set(true);
                        navigator.push(&crate::Route::Home);
                    }
                    Ok(r) => {
                        let text = r.text().await.unwrap_or_else(|_| "unknown".into());
                        error.set(format!("HTTP {}: {}", r.status(), text));
                    }
                    Err(err) => error.set(format!("Network error: {}", err)),
                }
            });
        })
    };

    html! {
        <div>
        <h1 class="headline">{ "Anmeldung" }</h1>
        <form {onsubmit}>
            <input
                placeholder="username"
                value={(*username).clone()}
                oninput={Callback::from(move |e: InputEvent| {
                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                    username.set(input.value());
                })}
            />
            <input
                type="password"
                placeholder="password"
                value={(*pwd).clone()}
                oninput={Callback::from(move |e: InputEvent| {
                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                    pwd.set(input.value());
                })}
            />
            <button type="submit" disabled={*loading}>{ if *loading { "Logging in..." } else { "Login" } }</button>
            if !error.is_empty() { <p style="color:red">{(*error).clone()}</p> }
        </form>
        </div>
    }
}

/// A component for fetching and displaying a list of all registered users.
///
/// This component retrieves a list of `FilteredUser` entities from the backend
/// via the `/api/users` endpoint and displays them. Each user entry includes a
/// link to view their individual details through `UserByID`.
///
/// # State
/// Uses `use_state` hooks to manage:
/// - `users`: A vector of `FilteredUser` structs to store the fetched user data.
/// - `error`: Any error message encountered during API calls.
/// - `loading`: A boolean indicating if user data is currently being fetched.
///
/// # Functionality
/// - **Data Fetching**: On component mount, fetches all users from `/api/users`.
/// - **Conditional Display**:
///   - If `loading` is true, displays "Loading...".
///   - If an `error` occurs, displays the error message.
///   - Otherwise, renders an unordered list of users.
/// - **Navigation**: Each user in the list is a link to [`crate::Route::UserByID`]
///   for viewing individual user details.
///
/// # Example
/// ```rust
/// html! {
///     <AllUsers />
/// }
/// ```
#[component(AllUsers)]
pub fn all_users_component() -> Html {
    let users = use_state(|| Vec::<FilteredUser>::new());
    let error = use_state(|| None::<String>);
    let loading = use_state(|| false);

    {
        let users = users.clone();
        let error = error.clone();
        let loading = loading.clone();

        use_effect_with((), move |_| {
            loading.set(true);
            spawn_local(async move {
                let url = format!("/api/users");
                match Request::get(&url).send().await {
                    Ok(response) if response.status() == 200 => {
                        match response.json::<Vec<FilteredUser>>().await {
                            Ok(u) => users.set(u),
                            Err(err) => error.set(Some(format!("Parse error: {}", err))),
                        }
                    }
                    Ok(response) => {
                        if let Ok(text) = response.text().await {
                            error.set(Some(text));
                        } else {
                            error.set(Some(format!("status {}", response.status())));
                        }
                    }
                    Err(err) => error.set(Some(format!("Network error: {}", err))),
                }
                loading.set(false);
            });
            || ()
        });
    }

    if *loading {
        html! {<p>{ "Loading" }</p>}
    } else if let Some(e) = &*error {
        html! { <p>{ format!("Error: {}", e) }</p> }
    } else {
        html! {
            <ul>
            { for users.iter().map(|t| html! {
                    <li key={t.id.to_string()}>
                        <Link<crate::Route> to={crate::Route::UserByID{id: t.id}}><h3>{ format!("{} {}- #{}", t.first_name, t.last_name, t.id) }</h3></Link<crate::Route>>
                    </li>
                })}
            </ul>
        }
    }
}

/// A component for displaying, updating, and deleting a single user by their ID.
///
/// This component fetches a specific user's details from the backend based on the
/// `id` provided in its `UserProps`. It allows administrators to view, modify
/// (first name, last name, username, admin status, and password), and delete user accounts.
///
/// # Props
/// - `id`: The `i16` ID of the user to fetch and display.
///
/// # State
/// Uses `use_state` hooks to manage:
/// - `user`: The fetched [`FilteredUser`] data, if available.
/// - `error`: Any error message encountered during initial user data fetching.
/// - `loading`: A boolean indicating if initial user data is being fetched.
/// - `first_name`, `last_name`, `username`, `make_admin`, `new_pwd`:
///   States for the update form fields, pre-filled with current user data.
/// - `saving`, `save_error`, `save_success`: States for the user update operation.
/// - `deleting`, `delete_error`: States for the user deletion operation.
///
/// # Functionality
/// - **Initial Data Fetching**: On component mount or `id` change, fetches user data from
///   `/api/users/:id`.
/// - **Form Initialization**: Populates the update form fields with the fetched user's
///   current details once loaded.
/// - **User Update**: The update form sends a PATCH request to `/api/users/:id` with a
///   `UserUpdateScheme` payload. On success, updates the displayed user data and shows a
///   success message.
/// - **User Deletion**: Includes a "Delete" button that, after user confirmation, sends
///   a DELETE request to `/api/users/:id`. On success, clears the user from display.
/// - **Error Handling**: Displays error messages for various API and network issues.
///
/// # Example
/// ```rust
/// html! {
///     <UserByID id={42} />
/// }
/// ```
#[component(UserByID)]
pub fn user_by_id_component(props: &UserProps) -> Html {
    let user = use_state(|| None::<FilteredUser>);
    let error = use_state(|| None::<String>);
    let loading = use_state(|| false);
    let id = props.id;

    {
        let user = user.clone();
        let error = error.clone();
        let loading = loading.clone();

        use_effect_with(id, move |id_ref| {
            loading.set(true);
            let user = user.clone();
            let error = error.clone();
            let id = *id_ref;
            spawn_local(async move {
                let url = format!("/api/users/{}", id);

                match Request::get(&url).send().await {
                    Ok(response) => {
                        let status = response.status();
                        if status == 200 {
                            match response.json::<FilteredUser>().await {
                                Ok(u) => user.set(Some(u)),
                                Err(err) => error.set(Some(format!("Parse error: {}", err))),
                            }
                        } else {
                            match response.json::<ApiError>().await {
                                Ok(ae) => error.set(Some(ae.message)),
                                Err(_) => {
                                    if let Ok(text) = response.text().await {
                                        error.set(Some(text));
                                    } else {
                                        error.set(Some(format!("Server error: {}", status)));
                                    }
                                }
                            }
                        }
                    }
                    Err(err) => error.set(Some(format!("Network error: {}", err))),
                }
                loading.set(false);
            });
            || ()
        });
    }

    let first_name = use_state(|| "".to_string());
    let last_name = use_state(|| "".to_string());
    let username = use_state(|| "".to_string());
    let make_admin = use_state(|| false);
    let new_pwd = use_state(|| String::new());
    let saving = use_state(|| false);
    let save_error = use_state(|| None::<String>);
    let save_success = use_state(|| false);

    {
        let user = user.clone();
        let first_name = first_name.clone();
        let last_name = last_name.clone();
        let username = username.clone();
        let make_admin = make_admin.clone();

        use_effect_with(user, move |user_ref| {
            if let Some(u) = &**user_ref {
                first_name.set(u.first_name.clone());
                last_name.set(u.last_name.clone());
                username.set(u.username.clone());
                make_admin.set(u.is_admin);
            }
            || ()
        });
    }

    let onsubmit = {
        let first_name = first_name.clone();
        let last_name = last_name.clone();
        let username = username.clone();
        let make_admin = make_admin.clone();
        let new_pwd = new_pwd.clone();
        let saving = saving.clone();
        let save_error = save_error.clone();
        let save_success = save_success.clone();
        let user_state = user.clone();

        Callback::from(move |e: SubmitEvent| {
            e.prevent_default();
            let first_name = (*first_name).clone();
            let last_name = (*last_name).clone();
            let username = (*username).clone();
            let make_admin = *make_admin;
            let new_pwd = (*new_pwd).clone();

            saving.set(true);
            save_error.set(None);
            save_success.set(false);

            let saving = saving.clone();
            let save_error = save_error.clone();
            let save_success = save_success.clone();
            let user_state = user_state.clone();
            let id = id;

            spawn_local(async move {
                let payload = UserUpdateScheme {
                    id: id,
                    first_name,
                    last_name,
                    username,
                    make_admin,
                    new_pwd,
                };

                let url = format!("/api/users/{}", id);
                let request = Request::patch(&url)
                    .header("Content-Type", "application/json")
                    .credentials(web_sys::RequestCredentials::Include)
                    .json(&payload)
                    .expect("Failed to construct Request");

                match request.send().await {
                    Ok(resp) if resp.status() == 200 => {
                        if let Ok(updated) = resp.json::<FilteredUser>().await {
                            user_state.set(Some(updated));
                        }
                        save_success.set(true);
                    }
                    Ok(resp) => {
                        let txt = resp.text().await.unwrap_or_else(|_| "Unknown".into());
                        save_error.set(Some(format!("HTTP {}: {}", resp.status(), txt)));
                    }
                    Err(err) => save_error.set(Some(format!("Network error: {}", err))),
                }
                saving.set(false);
            });
        })
    };

    let deleting = use_state(|| false);
    let delete_error = use_state(|| None::<String>);

    let ondelete = {
        let deleting = deleting.clone();
        let delete_error = delete_error.clone();
        let user_state = user.clone(); // or ticket
        let id = id;

        Callback::from(move |e: MouseEvent| {
            e.prevent_default();
            // confirm
            if !web_sys::window()
                .and_then(|w| {
                    w.confirm_with_message("Are you sure you want to delete this item?")
                        .ok()
                })
                .unwrap_or(false)
            {
                return;
            }

            deleting.set(true);
            delete_error.set(None);

            let deleting = deleting.clone();
            let delete_error = delete_error.clone();
            let user_state = user_state.clone();

            spawn_local(async move {
                let url = format!("/api/users/{}", id); // or /api/tickets/{}
                let req = Request::delete(&url).credentials(web_sys::RequestCredentials::Include);

                match req.send().await {
                    Ok(resp) if resp.status() == 200 || resp.status() == 204 => {
                        // remove local state or navigate away
                        user_state.set(None); // clears the shown item
                    }
                    Ok(resp) => {
                        let txt = resp.text().await.unwrap_or_else(|_| "Unknown".into());
                        delete_error.set(Some(format!("HTTP {}: {}", resp.status(), txt)));
                    }
                    Err(err) => delete_error.set(Some(format!("Network error: {}", err))),
                }
                deleting.set(false);
            });
        })
    };

    if *loading {
        html! {<p>{ "Loading" }</p>}
    } else if let Some(e) = &*error {
        html! { <p>{ format!("Error: {}", e) }</p> }
    } else if let Some(u) = &*user {
        html! {
            <div>
                <div>
                    <p><strong>{ "Vorname: " }</strong>{ &u.first_name }</p>
                    <p><strong>{ "Nachname: " }</strong>{ &u.last_name }</p>
                    <p><strong>{ "Benutzername: " }</strong>{ &u.username }</p>
                    <p><strong>{ "Ist Admin: " }</strong>{ u.is_admin }</p>
                </div>

                <h1>{ format!("User #{}", u.id) }</h1>
                <form onsubmit={onsubmit}>
                    <div>
                        <label>{ "Vorname" }
                            <input name="first_name"
                                value={(*first_name).clone()}
                                oninput={Callback::from(move |e: InputEvent| {
                                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                                    first_name.set(input.value());
                                })}
                            />
                        </label>
                    </div>
                    <div>
                        <label>{ "Nachname" }
                            <input name="last_name"
                                value={(*last_name).clone()}
                                oninput={Callback::from(move |e: InputEvent| {
                                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                                    last_name.set(input.value());
                                })}
                            />
                        </label>
                    </div>
                    <div>
                        <label>{ "Benutzername" }
                            <input name="username"
                                value={(*username).clone()}
                                oninput={Callback::from(move |e: InputEvent| {
                                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                                    username.set(input.value());
                                })}
                            />
                        </label>
                    </div>
                    <div>
                        <label>{ "Ist Admin" }
                            <input type="checkbox" name="make_admin" checked={*make_admin} onchange={Callback::from(move |e: Event| {
                                let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                                make_admin.set(input.checked());
                            })}/>
                        </label>
                    </div>
                    <div>
                        <label>{ "Neues Passwort (leer = unchanged)" }
                            <input name="new_pwd" type="password"
                                value={(*new_pwd).clone()}
                                oninput={Callback::from(move |e: InputEvent| {
                                    let input: web_sys::HtmlInputElement = e.target_unchecked_into();
                                    new_pwd.set(input.value());
                                })}
                            />
                        </label>
                    </div>

                    <button type="submit" disabled={*saving}>{ if *saving { "Speichern..." } else { "Speichern" } }</button>
                    if *save_success {
                        <p style="color:green">{ "Updated successfully" }</p>
                    }
                    if let Some(err) = &*save_error {
                        <p style="color:red">{ err.clone() }</p>
                    }
                </form>

                <button onclick={ondelete} disabled={*deleting}>
                    {if *deleting {"Löschen..."} else {"Löschen"}}
                </button>

                <Link<crate::Route> to={crate::Route::AllUsers}>{ "Zurück zur Benutzerübersicht" }</Link<crate::Route>>
                if let Some(err) = &*delete_error {
                    <p style="color:red">{ err.clone() }</p>
                }
            </div>
        }
    } else {
        html! { <p>{ "No ticket found." }</p> }
    }
}