use models::chat::messages;
use sea_orm::{ActiveModelTrait, EntityTrait, Set};
use uuid::Uuid;

use crate::services::service::ChatService;
use crate::share::notify;
use crate::share::realtime::RoomEvent;

const MAX_URLS_PER_MESSAGE: usize = 3;

/// 裁掉句尾标点，但保留括号配对时的右括号。
///
/// `https://en.wikipedia.org/wiki/Rust_(programming_language)` 末尾的 `)` 属于路径；
/// `(详见 https://example.com/a)` 末尾的 `)` 不属于。按括号计数决定去留。
fn trim_trailing_punctuation(value: &str) -> String {
    let mut end = value.len();
    while end > 0 {
        let Some(ch) = value[..end].chars().next_back() else {
            break;
        };
        let drop = match ch {
            ')' => value[..end].matches('(').count() < value[..end].matches(')').count(),
            ']' => value[..end].matches('[').count() < value[..end].matches(']').count(),
            '}' => value[..end].matches('{').count() < value[..end].matches('}').count(),
            '.' | ',' | '>' | '"' | '\'' | ';' | '!' | '?' | '。' | '，' | '、' | '）' | '】'
            | '》' | '」' | '』' => true,
            _ => false,
        };
        if !drop {
            break;
        }
        end -= ch.len_utf8();
    }
    value[..end].to_string()
}

impl ChatService {
    pub async fn unfurl_message(&self, room_id: Uuid, message_id: Uuid, content: String) {
        let urls = {
            let content = &content;
            let mut urls = Vec::new();
            for token in content.split_whitespace() {
                // 只裁掉 URL 前面的引用符号：括号可能是路径的一部分
                // （`.../Rust_(programming_language)`），先剥掉会把链接截断。
                let trimmed = token.trim_start_matches(|c: char| {
                    matches!(c, '(' | '[' | '{' | '<' | '"' | '\'' | '「' | '『' | '《')
                });
                if !(trimmed.starts_with("http://") || trimmed.starts_with("https://")) {
                    continue;
                }
                if trimmed.len() < 12 || trimmed.len() > 2048 {
                    continue;
                }
                let cleaned = trim_trailing_punctuation(trimmed);
                if cleaned.len() < 12 || cleaned.len() > 2048 {
                    continue;
                }
                if !urls.contains(&cleaned) {
                    urls.push(cleaned);
                }
                if urls.len() >= MAX_URLS_PER_MESSAGE {
                    break;
                }
            }
            urls
        };
        if urls.is_empty() {
            return;
        }
        let mut embeds = Vec::new();
        for url in urls {
            if let Some(value) = self.resolve_link(&url).await {
                embeds.push(value)
            }
        }
        if embeds.is_empty() {
            return;
        }
        let Some(row) = messages::Entity::find_by_id(message_id)
            .one(self.database.write())
            .await
            .ok()
            .flatten()
        else {
            return;
        };
        if row.deleted_at.is_some() {
            return;
        }
        if row.embeds.as_array().is_some_and(|arr| !arr.is_empty()) {
            return;
        }
        let mut am: messages::ActiveModel = row.into();
        am.embeds = Set(serde_json::json!(embeds));
        if am.update(self.database.write()).await.is_err() {
            return;
        }
        let Some(updated) = messages::Entity::find_by_id(message_id)
            .one(self.database.read())
            .await
            .ok()
            .flatten()
        else {
            return;
        };
        let Ok(items) = self.build_message_dto(vec![updated], 0).await else {
            return;
        };
        let Some(dto) = items.into_iter().next() else {
            return;
        };
        let Ok(payload) = serde_json::to_value(&dto) else {
            return;
        };
        let seq = notify::current_room_seq(self.database.read(), room_id).await;
        let event = RoomEvent::MessageEdited {
            room_id,
            seq,
            message: payload,
        };
        self.audience.realtime.publish_room(&event).await;
    }

    /// 解析单条链接，返回可直接塞进 `MessageDto::embeds` 的一项。
    ///
    /// `social` 的 resolver 链先跑静态平台注册表，未命中再走通用
    /// HTML / oEmbed / 直链媒体解析；这里只负责把结果转成消息 DTO。
    async fn resolve_link(&self, url: &str) -> Option<serde_json::Value> {
        let embed = social::unfurl(url).await.ok()?.into_iter().next()?;
        serde_json::to_value(embed).ok()
    }
}

pub fn spawn_unfurl(service: &ChatService, room_id: Uuid, message_id: Uuid, content: String) {
    if !content.contains("http://") && !content.contains("https://") {
        return;
    }
    let service = service.clone();
    let request_id = api::middleware::request_id();
    tokio::spawn(async move {
        api::middleware::with_request_id(
            request_id.as_deref(),
            service.unfurl_message(room_id, message_id, content),
        )
        .await;
    });
}

#[cfg(test)]
mod tests {
    use crate::services::messages::MessageEmbedDto;

    /// 平台 embed 必须能原样填进 `MessageDto::embeds`，否则聊天里收到的一直是
    /// 空数组 —— 这正是此前链接卡片链路断掉的位置。
    #[test]
    fn platform_embed_fits_message_dto() {
        let cases = [
            "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
            "https://open.spotify.com/track/4cOdK2wGLETKBW3PvgPWqT",
            "https://mp.weixin.qq.com/s/AbCdEfGhIjKlMn",
            "https://www.bilibili.com/video/BV1xx411c7mD",
            "https://cdn.example.com/clip.mp4",
            "https://item.taobao.com/item.htm?id=123456",
        ];
        for url in cases {
            let value = social::embed_json(url).unwrap_or_else(|| panic!("{url} did not resolve"));
            let dto: MessageEmbedDto = serde_json::from_value(value)
                .unwrap_or_else(|error| panic!("{url} did not fit the DTO: {error}"));
            assert_eq!(dto.url.as_deref(), Some(url));
            assert!(
                dto.html
                    .as_deref()
                    .is_some_and(|html| html.contains("gd-embed")),
                "{url} produced no embed html"
            );
        }
    }

    #[test]
    fn legacy_link_embed_still_deserializes() {
        let value = serde_json::json!({
            "type": "link",
            "url": "https://example.com/",
            "title": "Example",
            "description": "desc",
            "site_name": "Example",
        });
        let dto: MessageEmbedDto = serde_json::from_value(value).unwrap();
        assert_eq!(dto.embed_type, "link");
        assert_eq!(dto.title.as_deref(), Some("Example"));
        assert!(dto.html.is_none());
    }
}