use axum::{
    Form,
    extract::State,
    http::{HeaderMap, StatusCode},
    response::{Html, IntoResponse, Redirect, Response},
};

use crate::{AppState, services::authenticated_request};

use super::{
    loader::{LoadError, load_page, load_set_page},
    state::{ValidationForm, ValidationSetForm},
    ui,
};

pub(crate) async fn new_field_validation_page(State(state): State<AppState>, headers: HeaderMap) -> Response {
    render_loaded(load_page(state, &headers, ValidationForm::default(), false, None).await)
}

pub(crate) async fn new_validation_rule_page(State(state): State<AppState>, headers: HeaderMap) -> Response {
    render_loaded(load_page(state, &headers, ValidationForm::default(), true, None).await)
}

pub(crate) async fn new_validation_set_page(State(state): State<AppState>, headers: HeaderMap) -> Response {
    render_set_loaded(load_set_page(state, &headers, ValidationSetForm::default(), None).await)
}

pub(crate) async fn save_field_validation(
    State(state): State<AppState>, headers: HeaderMap, Form(form): Form<ValidationForm>,
) -> Response {
    let submitted = form.clone();
    if let Err(error) = load_page(state.clone(), &headers, submitted.clone(), false, None).await {
        return render_loaded(Err(error));
    }
    if cross_site(&headers) {
        return (StatusCode::FORBIDDEN, "Cross-site form submission rejected").into_response();
    }
    if !form.validation_set_name.trim().is_empty() {
        let request = match form.apply_set_request() {
            Ok(request) => request,
            Err(message) => return render_loaded(load_page(state, &headers, submitted, false, Some(message)).await),
        };
        let mut validations = state.validations;
        let request = match authenticated_request(&headers, request) {
            Ok(request) => request,
            Err(_) => return Redirect::to("/login").into_response(),
        };
        return match validations.apply_validation_set(request).await {
            Ok(response) if response.get_ref().success => Html(ui::render_success(&response.get_ref().message)).into_response(),
            Ok(response) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(&response.get_ref().message))).into_response(),
            Err(error) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(error.message()))).into_response(),
        };
    }
    let request = match form.field_request() {
        Ok(request) => request,
        Err(message) => return render_loaded(load_page(state, &headers, submitted, false, Some(message)).await),
    };
    let mut validations = state.validations;
    let request = match authenticated_request(&headers, request) {
        Ok(request) => request,
        Err(_) => return Redirect::to("/login").into_response(),
    };
    match validations.update_field_validation(request).await {
        Ok(response) if response.get_ref().success => Html(ui::render_success(&response.get_ref().message)).into_response(),
        Ok(response) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(&response.get_ref().message))).into_response(),
        Err(error) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(error.message()))).into_response(),
    }
}

pub(crate) async fn save_validation_rule(
    State(state): State<AppState>, headers: HeaderMap, Form(form): Form<ValidationForm>,
) -> Response {
    let submitted = form.clone();
    if let Err(error) = load_page(state.clone(), &headers, submitted.clone(), true, None).await {
        return render_loaded(Err(error));
    }
    if cross_site(&headers) {
        return (StatusCode::FORBIDDEN, "Cross-site form submission rejected").into_response();
    }
    let request = match form.rule_request() {
        Ok(request) => request,
        Err(message) => return render_loaded(load_page(state, &headers, submitted, true, Some(message)).await),
    };
    let mut validations = state.validations;
    let request = match authenticated_request(&headers, request) {
        Ok(request) => request,
        Err(_) => return Redirect::to("/login").into_response(),
    };
    match validations.upsert_validation_rule(request).await {
        Ok(response) if response.get_ref().success => Html(ui::render_success(&response.get_ref().message)).into_response(),
        Ok(response) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(&response.get_ref().message))).into_response(),
        Err(error) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(error.message()))).into_response(),
    }
}

pub(crate) async fn save_validation_set(
    State(state): State<AppState>, headers: HeaderMap, Form(form): Form<ValidationSetForm>,
) -> Response {
    let submitted = form.clone();
    if let Err(error) = load_set_page(state.clone(), &headers, submitted.clone(), None).await {
        return render_set_loaded(Err(error));
    }
    if cross_site(&headers) {
        return (StatusCode::FORBIDDEN, "Cross-site form submission rejected").into_response();
    }
    let request = match form.request() {
        Ok(request) => request,
        Err(message) => return render_set_loaded(load_set_page(state, &headers, submitted, Some(message)).await),
    };
    let mut validations = state.validations;
    let request = match authenticated_request(&headers, request) {
        Ok(request) => request,
        Err(_) => return Redirect::to("/login").into_response(),
    };
    match validations.upsert_validation_set(request).await {
        Ok(response) if response.get_ref().success => Html(ui::render_success(&response.get_ref().message)).into_response(),
        Ok(response) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(&response.get_ref().message))).into_response(),
        Err(error) => (StatusCode::UNPROCESSABLE_ENTITY, Html(ui::render_error(error.message()))).into_response(),
    }
}

fn render_set_loaded(
    result: Result<(crate::ui::Nav, ValidationSetForm, Option<String>), LoadError>,
) -> Response {
    match result {
        Ok((nav, form, error)) => {
            Html(ui::render_set_page(nav, &form, error.as_deref())).into_response()
        }
        Err(LoadError::Unauthenticated) => Redirect::to("/login").into_response(),
        Err(LoadError::Forbidden) => (StatusCode::FORBIDDEN, Html(ui::render_error("Validation-management permission is required."))).into_response(),
        Err(LoadError::Backend(message)) => (StatusCode::BAD_GATEWAY, Html(ui::render_error(&message))).into_response(),
    }
}

fn render_loaded(result: Result<super::state::ValidationPageState, LoadError>) -> Response {
    match result {
        Ok(page) => Html(ui::render_page(&page)).into_response(),
        Err(LoadError::Unauthenticated) => Redirect::to("/login").into_response(),
        Err(LoadError::Forbidden) => (StatusCode::FORBIDDEN, Html(ui::render_error("Validation-management permission is required."))).into_response(),
        Err(LoadError::Backend(message)) => (StatusCode::BAD_GATEWAY, Html(ui::render_error(&message))).into_response(),
    }
}

fn cross_site(headers: &HeaderMap) -> bool {
    headers.get("sec-fetch-site").is_some_and(|value| value == "cross-site")
}