use async_trait::async_trait;
use std::collections::HashMap;
use std::sync::Arc;
use async_std::sync::RwLock;
use futures_util::FutureExt;
use serde_json::json;

use crate::database::{Storage, Result, StorageError, ErrorKind, MicropubChannel};
use crate::indieauth::User;

#[derive(Clone)]
pub struct MemoryStorage {
    pub mapping: Arc<RwLock<HashMap<String, serde_json::Value>>>,
    pub channels: Arc<RwLock<HashMap<String, Vec<String>>>>
}

#[async_trait]
impl Storage for MemoryStorage {
    async fn read_feed_with_limit<'a>(&self, url: &'a str, after: &'a Option<String>, limit: usize, user: &'a Option<String>) -> Result<Option<serde_json::Value>> {
        todo!()
    }

    async fn update_post<'a>(&self, url: &'a str, update: serde_json::Value) -> Result<()> {
        let mut add_keys: HashMap<String, serde_json::Value> = HashMap::new();
        let mut remove_keys: Vec<String> = vec![];
        let mut remove_values: HashMap<String, Vec<serde_json::Value>> = HashMap::new();

        if let Some(delete) = update["delete"].as_array() {
            remove_keys.extend(delete.iter().filter_map(|v| v.as_str()).map(|v| v.to_string()));
        } else if let Some(delete) = update["delete"].as_object() {
            for (k, v) in delete {
                if let Some(v) = v.as_array() {
                    remove_values.entry(k.to_string()).or_default().extend(v.clone());
                } else {
                    return Err(StorageError::new(ErrorKind::BadRequest, "Malformed update object"));
                }
            }
        }
        if let Some(add) = update["add"].as_object() {
            for (k, v) in add {
                if v.is_array() {
                    add_keys.insert(k.to_string(), v.clone());
                } else {
                    return Err(StorageError::new(ErrorKind::BadRequest, "Malformed update object"));
                }
            }
        }
        if let Some(replace) = update["replace"].as_object() {
            for (k, v) in replace {
                remove_keys.push(k.to_string());
                add_keys.insert(k.to_string(), v.clone());
            }
        }
        let mut mapping = self.mapping.write().await;
        if let Some(mut post) = mapping.get(url) {
            if let Some(url) = post["see_other"].as_str() {
                if let Some(new_post) = mapping.get(url) {
                    post = new_post
                } else {
                    return Err(StorageError::new(ErrorKind::NotFound, "The post you have requested is not found in the database."));
                }
            }
            let mut post = post.clone();
            for k in remove_keys {
                post["properties"].as_object_mut().unwrap().remove(&k);
            }
            for (k, v) in remove_values {
                let k = &k;
                let props;
                if k == "children" {
                    props = &mut post;
                } else {
                    props = &mut post["properties"];
                }
                v.iter().for_each(|v| {
                    if let Some(vec) = props[k].as_array_mut() {
                        if let Some(index) = vec.iter().position(|w| w == v) {
                            vec.remove(index);
                        }
                    }
                });
            }
            for (k, v) in add_keys {
                let props;
                if k == "children" {
                    props = &mut post;
                } else {
                    props = &mut post["properties"];
                }
                let k = &k;
                if let Some(prop) = props[k].as_array_mut() {
                    if k == "children" {
                        v.as_array().unwrap().iter().cloned().rev().for_each(|v| prop.insert(0, v));
                    } else {
                        prop.extend(v.as_array().unwrap().iter().cloned());
                    }
                } else {
                    post["properties"][k] = v
                }
            }
            mapping.insert(post["properties"]["uid"][0].as_str().unwrap().to_string(), post);
        } else {
            return Err(StorageError::new(ErrorKind::NotFound, "The designated post wasn't found in the database."));
        }
        Ok(())
    }

    async fn delete_post<'a>(&self, url: &'a str) -> Result<()> {
        self.mapping.write().await.remove(url);
        Ok(())
    }

    async fn post_exists(&self, url: &str) -> Result<bool> {
        return Ok(self.mapping.read().await.contains_key(url))
    }

    async fn get_post(&self, url: &str) ->Result<Option<serde_json::Value>> {
        let mapping = self.mapping.read().await;
        match mapping.get(url) {
            Some(val) => {
                if let Some(new_url) = val["see_other"].as_str() {
                    match mapping.get(new_url) {
                        Some(val) => Ok(Some(val.clone())),
                        None => {
                            drop(mapping);
                            self.mapping.write().await.remove(url);
                            Ok(None)
                        }
                    }
                } else {
                    Ok(Some(val.clone()))
                }
            },
            _ => Ok(None)
        }
    }

    async fn get_channels(&self, user: &User) -> Result<Vec<MicropubChannel>> {
        match self.channels.read().await.get(&user.me.to_string()) {
            Some(channels) => Ok(futures_util::future::join_all(channels.iter()
                .map(|channel| self.get_post(channel)
                    .map(|result| result.unwrap())
                    .map(|post: Option<serde_json::Value>| {
                        if let Some(post) = post {
                            Some(MicropubChannel {
                                uid: post["properties"]["uid"][0].as_str().unwrap().to_string(),
                                name: post["properties"]["name"][0].as_str().unwrap().to_string()
                            })
                        } else { None }
                    })
                ).collect::<Vec<_>>()).await.into_iter().filter_map(|chan| chan).collect::<Vec<_>>()),
            None => Ok(vec![])
        }
        
    }

    async fn put_post<'a>(&self, post: &'a serde_json::Value) -> Result<()> {
        let mapping = &mut self.mapping.write().await;
        let key: &str;
        match post["properties"]["uid"][0].as_str() {
            Some(uid) => key = uid,
            None => return Err(StorageError::new(ErrorKind::Other, "post doesn't have a UID"))
        }
        mapping.insert(key.to_string(), post.clone());
        if post["properties"]["url"].is_array() {
            for url in post["properties"]["url"].as_array().unwrap().iter().map(|i| i.as_str().unwrap().to_string()) {
                if &url != key {
                    mapping.insert(url, json!({"see_other": key}));
                }
            }
        }
        if post["type"].as_array().unwrap().iter().any(|i| i == "h-feed") {
            // This is a feed. Add it to the channels array if it's not already there.
            println!("{:#}", post);
            self.channels.write().await.entry(post["properties"]["author"][0].as_str().unwrap().to_string()).or_insert(vec![]).push(key.to_string())
        }
        Ok(())
    }
}

impl MemoryStorage {
    pub fn new() -> Self {
        Self {
            mapping: Arc::new(RwLock::new(HashMap::new())),
            channels: Arc::new(RwLock::new(HashMap::new()))
        }
    }
}