//! Item embed handlers: buy button, product card, audio player.

use axum::{
    extract::{Path, Query, State},
    http::{header, HeaderValue},
    response::{IntoResponse, Response},
};
use serde::Deserialize;

use crate::{
    db::{self, ItemId},
    error::{AppError, Result},
    AppState,
};

/// Shared context fetched for all item embeds.
struct ItemEmbedContext {
    title: String,
    price_display: String,
    button_text: String,
    purchase_url: String,
    cover_image_url: Option<String>,
    creator_username: String,
    creator_display_name: String,
    description_excerpt: String,
    #[allow(dead_code)]
    item_type_label: String,
    /// Whether the item has audio (for player embed eligibility).
    has_audio: bool,
}

async fn fetch_item_embed_context(state: &AppState, item_id: ItemId) -> Result<ItemEmbedContext> {
    let item = db::items::get_item_by_id(&state.db, item_id)
        .await?
        .ok_or(AppError::NotFound)?;

    if !item.is_public {
        return Err(AppError::NotFound);
    }

    let project = db::projects::get_project_by_id(&state.db, item.project_id)
        .await?
        .ok_or(AppError::NotFound)?;

    let user = db::users::get_user_by_id(&state.db, project.user_id)
        .await?
        .ok_or(AppError::NotFound)?;

    if user.is_suspended() || user.is_deactivated() {
        return Err(AppError::NotFound);
    }

    let (price_display, button_text) = if item.price_cents == 0 {
        ("Free".to_string(), "Get".to_string())
    } else if item.pwyw_enabled {
        (format!("${:.2}+", item.price_cents as f64 / 100.0), "Buy".to_string())
    } else {
        (format!("${:.2}", item.price_cents as f64 / 100.0), "Buy".to_string())
    };

    let purchase_url = format!("{}/buy/{}", state.config.host_url, item_id);

    let description_excerpt = item.description.as_deref()
        .unwrap_or("")
        .chars()
        .take(150)
        .collect::<String>();

    Ok(ItemEmbedContext {
        title: item.title.clone(),
        price_display,
        button_text,
        purchase_url,
        cover_image_url: item.cover_image_url.clone(),
        creator_username: user.username.to_string(),
        creator_display_name: user.display_name.unwrap_or_else(|| user.username.to_string()),
        description_excerpt,
        item_type_label: item.item_type.label().to_string(),
        has_audio: item.audio_s3_key.is_some(),
    })
}

/// Set embed-specific caching. Framing + CSP for `/embed/*` are owned by the
/// global `security_headers_middleware` (which runs on the way out and
/// overwrites any X-Frame-Options/CSP set here), so this only sets Cache-Control
/// — the one header the middleware does not touch.
pub(super) fn set_embed_headers(response: &mut Response) {
    let headers = response.headers_mut();
    headers.insert(
        header::CACHE_CONTROL,
        HeaderValue::from_static("public, max-age=300"),
    );
}

// ─── Buy Button ─────────────────────────────────────────────────────────────

#[tracing::instrument(skip_all, name = "embed::item_button")]
/// GET /embed/i/{item_id}/button
pub(super) async fn item_button(
    State(state): State<AppState>,
    Path(item_id): Path<ItemId>,
) -> Result<Response> {
    let ctx = fetch_item_embed_context(&state, item_id).await?;

    let mut response = crate::templates::EmbedItemButtonTemplate {
        title: ctx.title,
        price_display: ctx.price_display,
        purchase_url: ctx.purchase_url,
        button_text: ctx.button_text,
        cover_image_url: ctx.cover_image_url,
    }
    .into_response();
    set_embed_headers(&mut response);
    Ok(response)
}

// ─── Product Card ───────────────────────────────────────────────────────────

#[derive(Debug, Deserialize)]
pub(super) struct CardQuery {
    pub layout: Option<String>,
}

#[tracing::instrument(skip_all, name = "embed::item_card")]
/// GET /embed/i/{item_id}/card
pub(super) async fn item_card(
    State(state): State<AppState>,
    Path(item_id): Path<ItemId>,
    Query(query): Query<CardQuery>,
) -> Result<Response> {
    let ctx = fetch_item_embed_context(&state, item_id).await?;
    let layout = query.layout.as_deref().unwrap_or("vertical");
    let is_horizontal = layout == "horizontal";

    let profile_url = format!("{}/u/{}", state.config.host_url, ctx.creator_username);

    let mut response = crate::templates::EmbedItemCardTemplate {
        title: ctx.title,
        price_display: ctx.price_display,
        purchase_url: ctx.purchase_url,
        button_text: ctx.button_text,
        cover_image_url: ctx.cover_image_url,
        creator_display_name: ctx.creator_display_name,
        profile_url,
        description_excerpt: ctx.description_excerpt,
        is_horizontal,
    }
    .into_response();
    set_embed_headers(&mut response);
    Ok(response)
}

// ─── Audio Player ───────────────────────────────────────────────────────────

#[tracing::instrument(skip_all, name = "embed::item_player")]
/// GET /embed/i/{item_id}/player
///
/// Audio preview player embed. Returns 404 for non-audio items.
#[tracing::instrument(skip_all, name = "embed::item_player")]
pub(super) async fn item_player(
    State(state): State<AppState>,
    Path(item_id): Path<ItemId>,
) -> Result<Response> {
    let ctx = fetch_item_embed_context(&state, item_id).await?;

    if !ctx.has_audio {
        return Err(AppError::NotFound);
    }

    // Preview URL would be /embed/i/{item_id}/preview.mp3 once ffmpeg generation is built.
    // For now, link to the item page — the player embed is a stub until preview generation ships.
    let preview_url = format!("{}/api/stream/{}", state.config.host_url, item_id);

    let mut response = crate::templates::EmbedItemPlayerTemplate {
        title: ctx.title,
        price_display: ctx.price_display,
        purchase_url: ctx.purchase_url,
        button_text: ctx.button_text,
        creator_display_name: ctx.creator_display_name,
        cover_image_url: ctx.cover_image_url,
        preview_url,
    }
    .into_response();
    set_embed_headers(&mut response);
    Ok(response)
}

#[cfg(test)]
mod tests {
    #[test]
    fn price_display_free() {
        let (price, btn) = if 0 == 0 {
            ("Free".to_string(), "Get".to_string())
        } else {
            unreachable!()
        };
        assert_eq!(price, "Free");
        assert_eq!(btn, "Get");
    }

    #[test]
    fn price_display_fixed() {
        let cents = 1999;
        let price = format!("${:.2}", cents as f64 / 100.0);
        assert_eq!(price, "$19.99");
    }

    #[test]
    fn price_display_pwyw() {
        let cents = 500;
        let price = format!("${:.2}+", cents as f64 / 100.0);
        assert_eq!(price, "$5.00+");
    }

    #[test]
    fn description_excerpt_truncation() {
        let long = "a".repeat(200);
        let excerpt: String = long.chars().take(150).collect();
        assert_eq!(excerpt.len(), 150);
    }

    #[test]
    fn description_excerpt_short() {
        let short = "Hello";
        let excerpt: String = short.chars().take(150).collect();
        assert_eq!(excerpt, "Hello");
    }
}