//! 内容库的查询组装：把统一的 node 树还原成前端 `types.ts` 想要的三种形态。
//!
//! 库里只有一套容器树（分区 → 分组），前端需要 `apps / posters / articles`
//! 的可辨识联合，那是**查询层按 `node.view_mode` 组装**的事。
//!
//! 所有关联都走业务键（`key`），SQL 里能直接看懂指向的是哪个分区 / 分组。

use std::collections::HashMap;

use rusqlite::Connection;
use serde_json::{Map, Value, json};

use crate::{
    db::map_error,
    error::StashError,
};

/// 条目行：与 `entry` 表的列一一对应
struct EntryRow {
    key: String,
    format: String,
    name: String,
    description: Option<String>,
    icon: Option<String>,
    href: Option<String>,
    cover: Option<String>,
    banner: Option<String>,
    badge: Option<String>,
    comment: Option<String>,
    summary: Option<String>,
    body: Option<String>,
    hot: bool,
    views: i64,
    likes: i64,
}

/// 分组树节点（新视图用）
struct TreeNode {
    key: String,
    parent: Option<String>,
    title: String,
    icon: Option<String>,
    bar_color: Option<String>,
    preview_limit: Option<i64>,
    sort: i64,
    enabled: bool,
}

/// 新的原子视图：完整分组树（多层、带条目），供新首页/侧栏/后台使用。
pub fn load_tree(conn: &Connection) -> Result<Value, StashError> {
    let mut stmt = conn
        .prepare(
            "SELECT key, parent_key, title, icon, bar_color, preview_limit, sort, enabled
             FROM node ORDER BY sort, key",
        )
        .map_err(map_error)?;

    let nodes = stmt
        .query_map([], |row| {
            Ok(TreeNode {
                key: row.get(0)?,
                parent: row.get(1)?,
                title: row.get(2)?,
                icon: row.get(3)?,
                bar_color: row.get(4)?,
                preview_limit: row.get(5)?,
                sort: row.get(6)?,
                enabled: row.get(7)?,
            })
        })
        .map_err(map_error)?
        .collect::<Result<Vec<_>, _>>()
        .map_err(map_error)?;

    drop(stmt);

    // 子节点索引（按 sort 已排好序）
    let mut children: HashMap<Option<String>, Vec<usize>> = HashMap::new();
    for (idx, node) in nodes.iter().enumerate() {
        children.entry(node.parent.clone()).or_default().push(idx);
    }

    let tags = load_all_tags(conn)?;

    fn render(
        conn: &Connection,
        nodes: &[TreeNode],
        children: &HashMap<Option<String>, Vec<usize>>,
        tags: &HashMap<String, Vec<String>>,
        idx: usize,
    ) -> Result<Value, StashError> {
        let node = &nodes[idx];
        let entries = load_node_entries(conn, &node.key)?;
        let items = entries
            .iter()
            .map(|entry| item_for(entry, tags))
            .collect::<Vec<_>>();

        let child_values = children
            .get(&Some(node.key.clone()))
            .map(|list| {
                list.iter()
                    .map(|child| render(conn, nodes, children, tags, *child))
                    .collect::<Result<Vec<_>, _>>()
            })
            .transpose()?
            .unwrap_or_default();

        Ok(json!({
            "key": node.key,
            "parentKey": node.parent,
            "title": node.title,
            "icon": node.icon.clone().unwrap_or_default(),
            "barColor": node.bar_color.clone().unwrap_or_default(),
            "previewLimit": node.preview_limit,
            "sort": node.sort,
            "enabled": node.enabled,
            "entries": items,
            "children": child_values,
        }))
    }

    let roots = children
        .get(&None)
        .map(|list| {
            list.iter()
                .map(|idx| render(conn, &nodes, &children, &tags, *idx))
                .collect::<Result<Vec<_>, _>>()
        })
        .transpose()?
        .unwrap_or_default();

    Ok(Value::Array(roots))
}

/// 全部条目标签（一次查询，树组装时用）
fn load_all_tags(conn: &Connection) -> Result<HashMap<String, Vec<String>>, StashError> {
    let mut stmt = conn
        .prepare("SELECT entry_key, label FROM entry_tag ORDER BY entry_key, sort")
        .map_err(map_error)?;

    let rows = stmt
        .query_map([], |row| {
            Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?))
        })
        .map_err(map_error)?
        .collect::<Result<Vec<_>, _>>()
        .map_err(map_error)?;

    let mut grouped: HashMap<String, Vec<String>> = HashMap::new();
    for (entry_key, label) in rows {
        grouped.entry(entry_key).or_default().push(label);
    }
    Ok(grouped)
}

/// 按条目自身的格式组装列表项。
fn item_for(entry: &EntryRow, tags: &HashMap<String, Vec<String>>) -> Value {
    let mut value = match entry.format.as_str() {
        "posters" => poster_item(entry, tags.get(&entry.key)),
        "articles" => article_item(entry, tags.get(&entry.key)),
        _ => app_item(entry),
    };
    if let Some(object) = value.as_object_mut() {
        object.insert("format".into(), json!(entry.format));
    }
    value
}

fn app_item(entry: &EntryRow) -> Value {
    let mut object = Map::new();
    object.insert("id".into(), json!(entry.key));
    object.insert("name".into(), json!(entry.name));
    // 列表卡片必须有副标题，空字符串比缺字段安全
    object.insert(
        "desc".into(),
        json!(entry.description.clone().unwrap_or_default()),
    );
    object.insert("icon".into(), json!(entry.icon.clone().unwrap_or_default()));
    object.insert(
        "href".into(),
        json!(entry.href.clone().unwrap_or_else(|| "#".to_string())),
    );

    insert_optional(&mut object, "cover", &entry.cover);
    insert_optional(&mut object, "banner", &entry.banner);
    insert_optional(&mut object, "badge", &entry.badge);
    insert_optional(&mut object, "comment", &entry.comment);

    // hot 只在为真时下发，前端判 `item.hot === true`
    if entry.hot {
        object.insert("hot".into(), json!(true));
    }

    object.insert("views".into(), json!(entry.views));
    object.insert("likes".into(), json!(entry.likes));

    Value::Object(object)
}

/// 海报条目：前端用 `title` 而不是 `name`。
fn poster_item(entry: &EntryRow, tags: Option<&Vec<String>>) -> Value {
    let mut object = Map::new();
    object.insert("id".into(), json!(entry.key));
    object.insert("title".into(), json!(entry.name));
    object.insert("cover".into(), json!(entry.cover.clone().unwrap_or_default()));

    if let Some(tags) = tags.filter(|tags| !tags.is_empty()) {
        object.insert("tags".into(), json!(tags));
    }

    insert_optional(&mut object, "comment", &entry.comment);
    insert_optional(&mut object, "summary", &entry.summary);
    insert_optional(&mut object, "href", &entry.href);

    object.insert("views".into(), json!(entry.views));
    object.insert("likes".into(), json!(entry.likes));

    Value::Object(object)
}

/// 图文条目：`meta` 来自 entry_tag，`body` 是 Markdown 正文。
fn article_item(entry: &EntryRow, meta: Option<&Vec<String>>) -> Value {
    let mut object = Map::new();
    object.insert("id".into(), json!(entry.key));
    object.insert("title".into(), json!(entry.name));
    object.insert(
        "desc".into(),
        json!(entry.description.clone().unwrap_or_default()),
    );
    object.insert("cover".into(), json!(entry.cover.clone().unwrap_or_default()));

    if let Some(meta) = meta.filter(|meta| !meta.is_empty()) {
        object.insert("meta".into(), json!(meta));
    }
    if let Some(body) = entry.body.as_ref().filter(|body| !body.trim().is_empty()) {
        object.insert("body".into(), json!(body));
    }
    insert_optional(&mut object, "href", &entry.href);

    Value::Object(object)
}

/// 可选字段：`None` 就不下发，前端用 `??` 兜底。
fn insert_optional(object: &mut Map<String, Value>, key: &str, value: &Option<String>) {
    if let Some(value) = value {
        object.insert(key.into(), json!(value));
    }
}

/// 取某个节点直接挂着的条目，按 `sort` 升序。
fn load_node_entries(conn: &Connection, node_key: &str) -> Result<Vec<EntryRow>, StashError> {
    let mut stmt = conn
        .prepare(
            "SELECT e.key, e.name, e.description, e.icon, e.href, e.cover,
                    e.banner, e.badge, e.comment, e.summary, e.body, e.hot, e.views, e.likes,
                    COALESCE(e.format, 'apps')
             FROM entry e
             WHERE e.node_key = ?1
             ORDER BY e.sort, e.key",
        )
        .map_err(map_error)?;

    let entries = stmt
        .query_map([node_key], |row| {
            Ok(EntryRow {
                key: row.get(0)?,
                name: row.get(1)?,
                description: row.get(2)?,
                icon: row.get(3)?,
                href: row.get(4)?,
                cover: row.get(5)?,
                banner: row.get(6)?,
                badge: row.get(7)?,
                comment: row.get(8)?,
                summary: row.get(9)?,
                body: row.get(10)?,
                hot: row.get(11)?,
                views: row.get(12)?,
                likes: row.get(13)?,
                format: row.get(14)?,
            })
        })
        .map_err(map_error)?
        .collect::<Result<Vec<_>, _>>()
        .map_err(map_error)?;

    Ok(entries)
}