use axum::Json;
use axum::extract::State;
use axum::http::StatusCode;
use axum::response::IntoResponse;
use axum_extra::extract::Cached;
use serde::{Deserialize, Serialize};
use serde_json::json;

use crate::facets::{FacetLimits, parse_facets_from_text, render_text_with_facets_html};
use crate::http::context::WebContext;
use crate::http::errors::WebError;
use crate::http::middleware_auth::Auth;

#[derive(Debug, Deserialize)]
pub(crate) struct PreviewDescriptionRequest {
    pub description: String,
}

#[derive(Debug, Serialize)]
pub(crate) struct PreviewDescriptionResponse {
    pub html: String,
}

/// Handler for previewing event descriptions with rendered facets
///
/// This endpoint accepts description text, parses facets (mentions, links, hashtags),
/// and returns rendered HTML showing how the description will appear to users.
pub(crate) async fn handle_preview_description(
    State(web_context): State<WebContext>,
    Cached(_auth): Cached<Auth>,
    Json(request): Json<PreviewDescriptionRequest>,
) -> Result<impl IntoResponse, WebError> {
    // Validate description length (same as create event validation)
    if request.description.trim().len() < 10 {
        return Ok((
            StatusCode::BAD_REQUEST,
            Json(json!({"error": "Description must be at least 10 characters"})),
        )
            .into_response());
    }

    if request.description.len() > 3000 {
        return Ok((
            StatusCode::BAD_REQUEST,
            Json(json!({"error": "Description must be no more than 3000 characters"})),
        )
            .into_response());
    }

    // Trim description to match create/edit behavior - facets must be parsed from the same text
    let description = request.description.trim();

    // Parse facets from the description
    let limits = FacetLimits::default();
    let facets =
        parse_facets_from_text(description, web_context.identity_resolver.as_ref(), &limits).await;

    // Render HTML with facets
    let html = render_text_with_facets_html(description, facets.as_ref(), &limits);

    // Convert newlines to <br> tags for proper display
    let html_with_breaks = html.replace('\n', "<br>");

    Ok((
        StatusCode::OK,
        Json(PreviewDescriptionResponse {
            html: html_with_breaks,
        }),
    )
        .into_response())
}