use clap::Parser;
use serde::{Deserialize, Serialize};
use std::{
    cmp::Ordering,
    io::{BufRead, Write},
};
use xdg::BaseDirectories;

mod cli;

fn main() {
    let args = cli::Args::parse();

    let xdg_dirs = BaseDirectories::with_prefix(env!("CARGO_PKG_NAME")).unwrap();

    let finished_tasks_file_path = xdg_dirs.place_data_file("finished_data.json").unwrap();

    let tasks_file_path = xdg_dirs.place_data_file("data.json").unwrap();
    let mut tasks: Vec<Task> = std::fs::File::open(&tasks_file_path)
        .map(|file| serde_json::from_reader(file).unwrap())
        .unwrap_or_default();

    let current_task_info_file_path = xdg_dirs.place_data_file("current.json").unwrap();
    let mut current_task_info: Option<CurrentTaskInfo> =
        std::fs::File::open(&current_task_info_file_path)
            .map(|file| serde_json::from_reader(file).unwrap())
            .unwrap_or_default();

    match args.command {
        cli::SubCommand::Add { link, name } => {
            tasks.push(Task { name, link });

            let mut file = std::fs::File::create(&tasks_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&tasks).unwrap())
                .unwrap();

            println!("added");
        }
        cli::SubCommand::Edit {
            idx,
            name,
            link,
            no_link,
        } => {
            if current_task_info.is_some() {
                panic!("You can edit task only when you don't have an active task, yet");
            }

            if idx == 0 || idx > tasks.len() {
                panic!("invalid index");
            }

            let mut task = &mut tasks[idx - 1];
            if let Some(name) = name {
                task.name = name;
            }
            if let Some(link) = link {
                task.link = Some(link);
            } else if no_link {
                task.link = None;
            }

            let mut file = std::fs::File::create(&tasks_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&tasks).unwrap())
                .unwrap();

            println!("changed");
        }
        cli::SubCommand::Remove { idx } => {
            if current_task_info.is_some() {
                panic!("You can remove task only when you don't have an active task, yet");
            }

            if idx == 0 || idx > tasks.len() {
                panic!("invalid index");
            }

            let task = &tasks[idx - 1];
            println!("You are deleting task:");
            println!("  {}", task.name);
            if let Some(ref link) = task.link {
                println!("  link: {}", link);
            }

            println!("In most cases you need to `finish` command");
            loop {
                print!("Do you still want to delete the task? (y/N): ");
                std::io::stdout().flush().unwrap();
                let mut stdin = std::io::stdin().lock();
                let mut buf = String::new();
                stdin.read_line(&mut buf).unwrap();
                match buf.chars().next().unwrap_or_default() {
                    '\r' | '\n' | 'n' | 'N' => return,
                    'y' | 'Y' => break,
                    _ => println!("Unrecognised answer. Please try again."),
                }
            }

            tasks.remove(idx - 1);

            let mut file = std::fs::File::create(&tasks_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&tasks).unwrap())
                .unwrap();

            println!("removed");
        }
        cli::SubCommand::List => {
            for (i, task) in tasks.iter().enumerate() {
                let idx = i + 1;

                match current_task_info {
                    Some(CurrentTaskInfo { task_idx, .. }) if task_idx == idx => print!("> "),
                    _ => print!("  "),
                }

                print!("{}. ", idx);
                if task.link.is_some() {
                    print!("(link) ");
                }
                println!("{}", task.name);
            }
        }
        cli::SubCommand::Priority {
            idx: target_idx,
            priority,
        } => {
            if current_task_info.is_some() {
                panic!("You can change priority only when you don't have an active task, yet");
            }

            if target_idx == 0 || target_idx > tasks.len() {
                panic!("invalid index");
            }

            let idx = match priority {
                cli::Priority::Before { idx } | cli::Priority::After { idx } => {
                    match target_idx.cmp(&idx) {
                        Ordering::Equal => return,
                        Ordering::Less => idx - 1,
                        Ordering::Greater => idx,
                    }
                }
            };
            if idx == 0 || idx > tasks.len() {
                panic!("invalid index");
            }

            let target = tasks.remove(target_idx - 1);

            match priority {
                cli::Priority::Before { .. } => {
                    tasks.insert(idx - 1, target);
                }
                cli::Priority::After { .. } => {
                    tasks.insert(idx, target);
                }
            }

            let mut file = std::fs::File::create(&tasks_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&tasks).unwrap())
                .unwrap();
        }
        cli::SubCommand::Start { idx, open } => {
            let idx = idx.unwrap_or(1);
            if idx == 0 || idx > tasks.len() {
                panic!("invalid index");
            }
            let task = &tasks[idx - 1];

            current_task_info.replace(CurrentTaskInfo {
                task_idx: idx,
                task: task.clone(),
            });

            let mut file = std::fs::File::create(&current_task_info_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&current_task_info).unwrap())
                .unwrap();
            println!("started");

            if let (Some(link), true) = (task.link.as_ref(), open) {
                log::debug!("opening link...");
                std::process::Command::new("xdg-open")
                    .arg(link)
                    .spawn()
                    .expect("failed to start");
                log::debug!("opened");
            }

            /*
            println!("starting...");
            println!("-- on start hook found");
            println!("-- running...");
            println!("> curl ...");
            println!("-- status was changed to \"In progress\" successfuly");
            */
        }
        cli::SubCommand::Pause => {
            if current_task_info.take().is_none() {
                panic!("You can use the pause subcommand only when you have an active task");
            }

            let mut file = std::fs::File::create(&current_task_info_file_path).unwrap();
            file.write_all(&serde_json::to_vec(&current_task_info).unwrap())
                .unwrap();
            println!("paused");
        }
        cli::SubCommand::Finish => match current_task_info.take() {
            None => {
                panic!("You can use the finish subcommand only when you have an active task")
            }
            Some(info) => {
                let mut finished_tasks: Vec<Task> = std::fs::File::open(&finished_tasks_file_path)
                    .map(|file| serde_json::from_reader(file).unwrap())
                    .unwrap_or_default();

                let task = tasks.remove(info.task_idx - 1);
                finished_tasks.push(task);

                let mut file = std::fs::File::create(&tasks_file_path).unwrap();
                file.write_all(&serde_json::to_vec(&tasks).unwrap())
                    .unwrap();

                let mut file = std::fs::File::create(&finished_tasks_file_path).unwrap();
                file.write_all(&serde_json::to_vec(&finished_tasks).unwrap())
                    .unwrap();

                let mut file = std::fs::File::create(&current_task_info_file_path).unwrap();
                file.write_all(&serde_json::to_vec(&current_task_info).unwrap())
                    .unwrap();

                println!("finished");
            }
        },
        cli::SubCommand::Status => match current_task_info {
            None => {
                panic!("You don't have an active task.");
            }
            Some(info) => {
                println!("Information about your current task:");
                println!("  {}", info.task.name);
                if let Some(link) = info.task.link {
                    println!("  link: {}", link);
                }
            }
        },
    }
}

#[derive(Deserialize, Serialize, Clone)]
struct Task {
    name: String,
    link: Option<String>,
    // created_at
}

#[derive(Deserialize, Serialize)]
struct CurrentTaskInfo {
    task_idx: usize,
    task: Task,
    // started_at
}