const messages = new Map();
const users = new Map();
let sent = false;
const host = location.protocol + "//" + location.host;

// const xhttp_worker = new Worker("xhttp.js");


function xhttp_request(location) {
    let f = fetch(`${host}/api/${location}`);
    return f.then((response) => response.json());

}

function xhttp_post(location, json) {
    let f = fetch(`${host}/api/${location}`, {
        method: "POST",
        headers: {"Content-Type": "application/json"},
        body: json
    })

    return f.then((response) => response.json());
}


async function format_message(m) {
    var s;
    var sender = await get_user_name(m.sender);
    var sclass = "";

    if (m.deleted) {
        m.message = "*deleted*"
        sclass = "deleted"
    }
    s = `<span title="${m.id}" class="message ${sclass}" id="${m.id}">${format_date(m.date)}|${sender}: ${m.message}</span>`

    return s
}

function format_time(t) {
    let as_str = `${t}`;
    if (as_str.length < 2) {
        return `0${t}`
    } else {
        return `${t}`
    }
}

function format_date(d) {
    let date = new Date(d * 1000);
    let hours = format_time(date.getHours());
    let minutes = format_time(date.getMinutes());
    let seconds = format_time(date.getSeconds());
    return `${hours}:${minutes}:${seconds}`;
}

function send() {
    var input = document.getElementById("input").value;
    let user_id = get_user_from_name().then((user_id) => {
        if (user_id == undefined) {
            alert("User not found")
            return undefined
        }
    
        let message = JSON.stringify({"sender": user_id, "message": input})
    
        var id = xhttp_post("send_message", message).then((id) => {
            get_message(id.Ok);
        
            document.getElementById("input").value = ""
            sent = true
        })
    });
}

function get_newest_cache_id() {
    let last = -1;
    for (k of messages.keys()) {
        if (k > last) {
            last = k
        }
    }

    if (last == -1) {
        return undefined
    } else {
        return last
    }
}

// Returns message list
function get_newest_messages() {
    xhttp_request("get_message_id_newest").then(async (newest_id) => {
        let newest_cache_id = get_newest_cache_id();
    
        if (newest_id.Err) {
            return
        } else {
            newest_id = newest_id.Ok
        }
    
    
        let final_array = [];
    
        if (newest_id == newest_cache_id) {
            return
        }
    
        if (newest_cache_id == undefined) {
            let id = newest_id;
            if (id - 25 < 0) {
                get_message(0)
            } else {
                get_message(newest_id - 25)
            }
            return get_newest_messages()
        }
        
        if (newest_id > newest_cache_id) {
            let delta = newest_id - newest_cache_id ;
            if (delta > 25) {
                let oldest = newest_id - 25;
                let newest = delta;
    
    
                let list = get_message_list(oldest, newest);
                for (x of list.values()) {
                    final_array.push(x)
                }
    
                newest_id = oldest;
                if (oldest - 25 < 0) {
                    newest_cache_id = 0
                } else {
                    newest_cache_id = oldest - 25
                }
            }
        }
    
        let list = await get_message_list(newest_cache_id, newest_id)
        for (x of list.values()) {
            final_array.push(x)
        }
    
        // Insert all values into the message map
        for (x of final_array.values()) {
            messages.set(x.id, x)
        }
    
        chatwindow().then()
    });
}

async function get_message_list(oldest, newest) {
    let data = await xhttp_request(`get_message_list/${oldest}/${newest}`).then();
    let req = data.Ok;
    return req
}

// Returns dom
function get_message(id) {
    let cached = messages.get(id)
    if (cached != undefined) {
        return to_dom(format_message(cached))
    }

    // Get message
    xhttp_request("get_message/" + id).then((data) => {
        if (data.Ok != undefined) {
            let msg = data.Ok;
            messages.set(msg.id, msg)
            
            chatwindow(msg.id)
        }
    })
}

async function get_user_from_name() {
    let v = document.getElementById("username").value;

    for (x of users.values()) {
        if (x.username == v) {
            return x.id
        }
    }


    let user = await xhttp_post("get_user_by_name", JSON.stringify(v));
    if (user.Ok) {
        users.set(user.id, user)
        return user.Ok.id
    } else {
        return await create_user(v)
    }
}

async function create_user(username) {
    let response = await xhttp_post("create_user", JSON.stringify(username));
    if (response.Ok != undefined) {
        await get_user_name(response.Ok);
        return response.Ok

    } else {
        alert("Could not create user")
        return undefined
    }
}

async function get_user_name(id) {
    let cached = users.get(id)
    if (cached != undefined) {
        return cached.username
    }


    let data = await xhttp_request("get_user/" + id,);
    let user = data.Ok;

    users.set(user.id, user)

    return user.username
}

// Returns dom
function to_dom(x) {
    // Pretty hacky if I do say so myself
    let dom = new DOMParser().parseFromString(x, "text/html").firstChild.lastChild.firstChild;
    return dom
}

async function chatwindow(hash = undefined) {
    let window = document.getElementById("chatwindow");
    let pre_scroll = window.scrollHeight - window.clientHeight;
    window.innerHTML = "";

    let array = [];

    for (v of messages.values()) {
        array.push(v);
    }

    array.sort(
        function(a, b) {
            return a.id - b.id
        }
    );

    let old_date = new Date(0);
    let latest_v;
    for (v of array) {
        latest_v = v;
        let date = new Date(v.date * 1000);
        if (date.getDate() > old_date.getDate() || date.getFullYear() > old_date.getFullYear() || date.getMonth() > date.getMonth()) {
            old_date = date;
            window.append(to_dom(`<span class="date">${date.getDate()}/${date.getMonth()}/${date.getFullYear()}</span>`))
        }

        let data = await format_message(v).then()
        let dom = to_dom(data);

        window.appendChild(dom);

    }
    
    if (window.scrollTop == pre_scroll) {
        if (latest_v != undefined && hash == undefined) {
            document.getElementById(v.id).scrollIntoView();
        }
    } else {
        document.getElementById("new_messages").style.display = "unset"
    }

    if (hash != undefined) {
        document.getElementById(hash).scrollIntoView();
    }
}

function onscrollchat() {
    let window = document.getElementById("chatwindow");
    let pre_scroll = window.scrollHeight - window.clientHeight;

    if (window.scrollTop == pre_scroll) {
        document.getElementById("new_messages").style.display = "";
    }
}

function inputkey(event) {
    let window = document.getElementById("input");

    // If the cursor pos is at the end of the textarea
    let comp = window.selectionEnd - window.value.length

    let key = event.key
    let shift = event.shiftKey;
    if (key == "Enter" && !shift && comp == 0) {
        send()
    }
}

function clearnewlineinput() {
    let window = document.getElementById("input");

    if (window.value == "\n" && sent == true) {
        window.value = ""
        sent = false
    }
}

function onload() {
    xhttp_request("").then((server_info) => {

        document.getElementById("info").innerHTML += server_info.version + ", " + server_info.name + ", users: " + server_info.users;
    
        // Get ready for websockets implementation in rocket_test 0.3
        if (server_info.version[2] < 3 ) {
            const interval = setInterval(get_newest_messages, 1000);
        } else {
            // Initiate websocket "polling"
        }
    })
}