//! # Posts helper
//!
//! @author Pierre Hubert

use crate::constants::database_tables_names::POSTS_TABLE;
use crate::data::error::ResultBoxError;
use crate::data::post::{Post, PostVisibilityLevel};
use crate::data::user::UserID;
use crate::helpers::{database, friends_helper};

impl PostVisibilityLevel {
    pub fn to_db(&self) -> u32 {
        match self {
            PostVisibilityLevel::VISIBILITY_PUBLIC => 1,
            PostVisibilityLevel::VISIBILITY_FRIENDS => 2,
            PostVisibilityLevel::VISIBILITY_USER => 3,
            PostVisibilityLevel::VISIBILITY_GROUP_MEMBERS => 50,
        }
    }
}


pub struct PostsQuery {
    /// The ID of the user making the request
    user_id: Option<UserID>,

    /// Maximum number of posts to get
    limit: u64,

    /// Starting post
    start_from: u64,
}

impl PostsQuery {
    /// Construct a new request
    pub fn new(user_id: Option<UserID>) -> PostsQuery {
        PostsQuery {
            user_id,
            limit: 10,
            start_from: 0,
        }
    }

    /// Start starting point
    pub fn set_start_from(mut self, start_from: u64) -> PostsQuery {
        self.start_from = start_from;
        self
    }

    /// Set the limit for this query
    pub fn set_limit(mut self, limit: u64) -> PostsQuery {
        self.limit = limit;
        self
    }

    /// Get the posts of a user
    pub fn get_user(self, user_id: &UserID) -> ResultBoxError<Vec<Post>> {
        get_user(&self, user_id)
    }
}

/// Get the posts of `target_id`
fn get_user(query: &PostsQuery, target_id: &UserID) -> ResultBoxError<Vec<Post>> {
    // Max user visibility
    let mut level = PostVisibilityLevel::VISIBILITY_PUBLIC;

    if let Some(user_id) = &query.user_id {
        if user_id == target_id {
            level = PostVisibilityLevel::VISIBILITY_USER;
        } else if friends_helper::are_friend(user_id, target_id)? {
            level = PostVisibilityLevel::VISIBILITY_FRIENDS;
        }
    }

    // Start request
    let mut db_query = database::QueryInfo::new(POSTS_TABLE);
    let mut custom_where = String::new();

    // Preprocess conditions

    // ============= PERMISSION CONDITIONS =================
    custom_where.push_str("((niveau_visibilite <= ?) ");
    db_query = db_query.add_custom_where_argument_u32(level.to_db());

    // Add user posts (if signed in)
    if let Some(user_id) = &query.user_id {
        custom_where.push_str(" OR (ID_amis = ?) ");
        db_query = db_query.add_custom_where_argument_user_id(user_id);
    }

    custom_where.push_str(")");
    // ============= /PERMISSION CONDITIONS =================


    // ============== START POINT CONDITION =================
    if query.start_from != 0 {
        custom_where.push_str(" AND ID <= ?");
        db_query = db_query.add_custom_where_argument_u64(query.start_from);
    }
    // ============== /START POINT CONDITION ================


    // Perform the request
    db_query
        .cond_user_id("ID_personne", target_id)
        .cond_u64("group_id", 0)
        .set_custom_where(&custom_where)
        .set_order("ID DESC")
        .set_limit(query.limit)
        .exec(db_to_post)
}

/// Turn a post into a database entry
fn db_to_post(res: &database::RowResult) -> ResultBoxError<Post> {
    Ok(Post {
        id: res.get_u64("ID")?
    })
}