use crate::util::file_util::{get_children, get_directory, load_file, save_file};
use json::{self, JsonValue, array, object};
use std::fs::{self};
use std::path::Path;

use crate::gui::log_panel::log_message;

pub enum MessageState {
    Read,
    Received,
    Sending,
    Error,
}

impl MessageState {
    fn as_str(&self) -> &'static str {
        match self {
            MessageState::Read => "READ",
            MessageState::Received => "RECEIVED",
            MessageState::Sending => "SENDING",
            MessageState::Error => "ERROR",
        }
    }
}

pub fn add_message(
    send_time: u128,
    storage_owner_is_sender: bool,
    storage_owner: i64,
    external_user: i64,
    message: &str,
) {
    let user_dir = format!(
        "{}/users/{}/chats/{}",
        get_directory(),
        storage_owner,
        external_user
    );

    if let Err(e) = fs::create_dir_all(&user_dir) {
        log_message(format!("Failed to create chat directory: {}", e));
        return;
    }

    let mut chunk_index = 0;
    let mut message_chunk = array![];

    // find latest chunk not full (max 800 msgs)
    loop {
        let file_name = format!("msgs_{}.json", chunk_index);
        let file_content = load_file(&user_dir, &file_name);

        if !file_content.is_empty() {
            if let Ok(current_chunk) = json::parse(&file_content) {
                if current_chunk.is_array() && current_chunk.len() < 800 {
                    message_chunk = current_chunk;
                    break;
                }
            } else {
                log_message(format!("Failed to parse existing JSON file: {}", file_name));
            }
        } else {
            break;
        }

        chunk_index += 1;
        if chunk_index > 1000 {
            log_message(format!("Too many message chunks. Aborting add."));
            return;
        }
    }

    let json_obj = object! {
        "timestamp" => send_time as i64,
        "content" => message,
        "sent_by_self" => storage_owner_is_sender,
        "message_state" => MessageState::Sending.as_str()
    };

    if let Err(e) = message_chunk.push(json_obj) {
        log_message(format!("Failed to push new message into JSON array: {}", e));
        return;
    }

    let file_name = format!("msgs_{}.json", chunk_index);
    save_file(&user_dir, &file_name, &message_chunk.dump());
}
pub fn change_message_state(
    storage_owner: i64,
    external_user: i64,
    timestamp: i64,
    new_state: MessageState,
) -> std::io::Result<()> {
    let user_dir = format!("users/{}/chats/{}", storage_owner, external_user);
    let path = Path::new(&user_dir);

    if !path.exists() {
        return Ok(());
    }

    let entries = fs::read_dir(path)?;
    for entry in entries {
        let entry = entry?;
        let fname = entry.file_name();
        let fname_str = fname.to_string_lossy();

        if fname_str.starts_with("msgs_") && fname_str.ends_with(".json") {
            let file_content = load_file(&user_dir, &fname_str);
            if file_content.is_empty() {
                continue;
            }

            if let Ok(mut chunk) = json::parse(&file_content) {
                let mut modified = false;
                for i in 0..chunk.len() {
                    if chunk[i]["message_time"].as_i64() == Some(timestamp) {
                        chunk[i]["message_state"] = JsonValue::from(new_state.as_str());
                        modified = true;
                        break;
                    }
                }

                if modified {
                    save_file(&user_dir, &fname_str, &chunk.dump());
                    break;
                }
            }
        }
    }
    Ok(())
}

pub fn get_messages(
    storage_owner: i64,
    external_user: i64,
    loaded_messages: i64,
    amount: i64,
) -> JsonValue {
    let mut messages = array![];

    let mut latest_chunk_index: i32 = -1;
    let files = get_children(&format!("users/{}/chats/{}", storage_owner, external_user));

    for entry in files {
        if let Some(num) = {
            entry
                .strip_prefix("msgs_")
                .and_then(|s| s.strip_suffix(".json"))
        } {
            if let Ok(index) = num.parse::<i32>() {
                if index > latest_chunk_index {
                    latest_chunk_index = index;
                }
            }
        }
    }

    if latest_chunk_index == -1 {
        return messages;
    }

    let mut to_skip = loaded_messages;
    let mut needed = amount;

    for chunk_index in (0..=latest_chunk_index).rev() {
        if needed == 0 {
            break;
        }
        let file_name = format!("msgs_{}.json", chunk_index);
        let file_content = load_file(
            &format!("users/{}/chats/{}", storage_owner, external_user),
            &file_name,
        );
        if file_content.is_empty() {
            continue;
        }
        if let Ok(chunk) = json::parse(&file_content) {
            for i in (0..chunk.len()).rev() {
                if needed == 0 {
                    break;
                }
                if to_skip > 0 {
                    to_skip -= 1;
                    continue;
                }
                messages.push(chunk[i].clone()).unwrap();
                needed -= 1;
            }
        }
    }

    messages
}