mod attrs;
mod errors;
mod fzf;
mod stack;
mod task;
mod util;
mod workspace;
use clap_complete::{Shell, generate};
use errors::Result;
use std::io::{self, Write};
use std::path::PathBuf;
use std::process::exit;
use std::str::FromStr as _;
use std::{env::current_dir, io::Read};
use task::ParsedLink;
use workspace::{Id, Task, TaskIdentifier, Workspace};

//use smol;
//use iocraft::prelude::*;
use clap::{Args, CommandFactory, Parser, Subcommand};
use edit::edit as open_editor;

fn default_dir() -> PathBuf {
    current_dir().unwrap()
}

fn parse_id(s: &str) -> std::result::Result<Id, &'static str> {
    Id::from_str(s).map_err(|_| "Unable to parse tsk- ID")
}

#[derive(Parser)]
// TODO: add long_about
#[command(version, about)]
struct Cli {
    /// Override the tsk root directory.
    #[arg(short = 'C', env = "TSK_ROOT", value_name = "DIR")]
    dir: Option<PathBuf>,
    // TODO: other global options
    #[command(subcommand)]
    command: Commands,
}

#[derive(Subcommand)]
enum Commands {
    /// Initializes a .tsk workspace in the current effective directory, which defaults to PWD.
    Init,
    /// Creates a new task, automatically assigning it a unique identifider and persisting
    Push {
        /// Whether to open $EDITOR to edit the content of the task. The first line if the
        /// resulting file will be the task's title. The body follows the title after two newlines,
        /// similr to the format of a commit message.
        #[arg(short = 'e', default_value_t = false)]
        edit: bool,

        /// The body of the task. It may be specified as either a string using quotes or the
        /// special character '-' to read from stdin.
        #[arg(short = 'b')]
        body: Option<String>,

        /// The title of the task as a raw string. It mus be proceeded by two dashes (--).
        #[command(flatten)]
        title: Title,
    },
    /// Creates a new task just like `push`, but instead of putting it at the top of the stack, it
    /// puts it at the bottom
    Append {
        /// Whether to open $EDITOR to edit the content of the task. The first line if the
        /// resulting file will be the task's title. The body follows the title after two newlines,
        /// similr to the format of a commit message.
        #[arg(short = 'e', default_value_t = false)]
        edit: bool,

        /// The body of the task. It may be specified as either a string using quotes or the
        /// special character '-' to read from stdin.
        #[arg(short = 'b')]
        body: Option<String>,

        /// The title of the task as a raw string. It mus be proceeded by two dashes (--).
        #[command(flatten)]
        title: Title,
    },
    /// Print the task stack. This will include just TSK-IDs and the title.
    List {
        /// Whether to list all tasks in the task stack. If specified, -c / count is ignored.
        #[arg(short = 'a', default_value_t = false)]
        all: bool,
        #[arg(short = 'c', default_value_t = 10)]
        count: usize,
    },

    /// Swaps the top two tasks on the stack. If there are less than 2 tasks on the stack, there is
    /// no effect.
    Swap,

    /// Open up an editor to modify the task with the given ID.
    Edit {
        #[command(flatten)]
        task_id: TaskId,
    },

    /// Generates completion for a given shell.
    Completion {
        #[arg(short = 's')]
        shell: Shell,
    },

    /// Use fuzzy finding with `fzf` to search for a task
    Find {
        #[command(flatten)]
        args: FindArgs,
        /// Whether to print the a shortened tsk ID (just the integer portion). Defaults to *false*
        #[arg(short = 'f', default_value_t = false)]
        short_id: bool,
    },

    /// Prints the contents of a task, parsing the body as rich text and formatting it using ANSI
    /// escape sequences.
    Show {
        /// Shows raw file attributes for the file
        #[arg(short = 'x', default_value_t = false)]
        show_attrs: bool,

        #[arg(short = 'R', default_value_t = false)]
        raw: bool,
        /// The [TSK-]ID of the task to display
        #[command(flatten)]
        task_id: TaskId,
    },

    /// Follow a link that is parsed from a task body. It may be an internal or external link (ie.
    /// a url or a wiki-style link using double square brackets). When using the `tsk show`
    /// command, links that are successfully parsed get a numeric superscript that may be used to
    /// address the link. That number should be supplied to the -l/link_index where it will be
    /// subsequently followed opened or shown.
    Follow {
        /// The task whose body will be searched for links.
        #[command(flatten)]
        task_id: TaskId,
        /// The index of the link to open. Must be supplied.
        #[arg(short = 'l', default_value_t = 1)]
        link_index: usize,
        /// When opening an internal link, whether to show or edit the addressed task.
        #[arg(short = 'e', default_value_t = false)]
        edit: bool,
    },

    /// Drops the task on the top of the stack and archives it.
    Drop {
        /// The [TSK-]ID of the task to drop.
        #[command(flatten)]
        task_id: TaskId,
    },

    /// Moves the 3rd item on the stack to the front of the stack, shifting everything else down by
    /// one. If there are less than 3 tasks on the stack, has no effect.
    Rot,
    /// Moves the task on the top of the stack back behind the 2nd element, shifting the next two
    /// task up.
    Tor,

    /// Prioritizes an arbitrary task to the top of the stack.
    Prioritize {
        /// The [TSK-]ID to prioritize. If it exists, it is moved to the top of the stack.
        #[command(flatten)]
        task_id: TaskId,
    },

    /// Deprioritizes a task to the bottom of the stack.
    Deprioritize {
        /// The [TSK-]ID to deprioritize. If it exists, it is moved to the bottom of the stack.
        #[command(flatten)]
        task_id: TaskId,
    },
}

#[derive(Args)]
#[group(required = true, multiple = false)]
struct Title {
    /// The title of the task. This is useful for when you also wish to specify the body of the
    /// task as an argument (ie. with -b).
    #[arg(short, value_name = "TITLE")]
    title: Option<String>,

    #[arg(value_name = "TITLE")]
    title_simple: Option<Vec<String>>,
}

#[derive(Args)]
#[group(required = false, multiple = false)]
struct TaskId {
    /// The ID of the task to select as a plain integer.
    #[arg(short = 't', value_name = "ID")]
    id: Option<u32>,

    /// The ID of the task to select with the 'tsk-' prefix.
    #[arg(short = 'T', value_name = "TSK-ID", value_parser = parse_id)]
    tsk_id: Option<Id>,

    /// Selects a task relative to the top of the stack.
    /// If no option is specified, the task selected will be the top of the stack.
    #[arg(short = 'r', value_name = "RELATIVE", default_value_t = 0)]
    relative_id: u32,

    #[command(flatten)]
    find: Find,
}

/// Use fuzzy finding to search for and select a task.
/// Does not support searching task bodies or archived tasks.
#[derive(Args)]
#[group(required = false, multiple = true)]
struct Find {
    /// Use fuzzy finding to select a task.
    #[arg(short = 'f', value_name = "FIND", default_value_t = false)]
    find: bool,
    #[command(flatten)]
    args: FindArgs,
}

#[derive(Args)]
#[group(required = false, multiple = false)]
struct FindArgs {
    /// Exclude the contents of tasks in the search criteria.
    #[arg(short = 'b', default_value_t = false)]
    exclude_body: bool,
    /* TODO: implement this
    /// Include archived tasks in the search criteria. Combine with `-b` to include archived
    /// bodies in the search criteria.
    #[arg(short = 'a', default_value_t = false)]
    search_archived: bool,
    */
}

impl From<TaskId> for TaskIdentifier {
    fn from(value: TaskId) -> Self {
        if let Some(id) = value.id.map(Id::from).or(value.tsk_id) {
            TaskIdentifier::Id(id)
        } else if value.find.find {
            TaskIdentifier::Find {
                exclude_body: value.find.args.exclude_body,
                archived: false,
            }
        } else {
            TaskIdentifier::Relative(value.relative_id)
        }
    }
}

fn main() {
    let cli = Cli::parse();
    let dir = cli.dir.unwrap_or(default_dir());
    let var_name = match cli.command {
        Commands::Init => command_init(dir),
        Commands::Push { edit, body, title } => command_push(dir, edit, body, title),
        Commands::Append { edit, body, title } => command_append(dir, edit, body, title),
        Commands::List { all, count } => command_list(dir, all, count),
        Commands::Swap => command_swap(dir),
        Commands::Show {
            task_id,
            raw,
            show_attrs,
        } => command_show(dir, task_id, show_attrs, raw),
        Commands::Follow {
            task_id,
            link_index,
            edit,
        } => command_follow(dir, task_id, link_index, edit),
        Commands::Edit { task_id } => command_edit(dir, task_id),
        Commands::Completion { shell } => command_completion(shell),
        Commands::Drop { task_id } => command_drop(dir, task_id),
        Commands::Find { args, short_id } => command_find(dir, short_id, args),
        Commands::Rot => Workspace::from_path(dir).unwrap().rot(),
        Commands::Tor => Workspace::from_path(dir).unwrap().tor(),
        Commands::Prioritize { task_id } => command_prioritize(dir, task_id),
        Commands::Deprioritize { task_id } => command_deprioritize(dir, task_id),
    };
    let result = var_name;
    match result {
        Ok(_) => exit(0),
        Err(e) => {
            eprintln!("{e}");
            exit(2);
        }
    }
}

fn taskid_from_tsk_id(tsk_id: Id) -> TaskId {
    TaskId {
        tsk_id: Some(tsk_id),
        id: None,
        relative_id: 0,
        find: Find {
            find: false,
            args: FindArgs { exclude_body: true },
        },
    }
}

fn command_init(dir: PathBuf) -> Result<()> {
    Workspace::init(dir)
}

fn create_task(
    workspace: &mut Workspace,
    edit: bool,
    body: Option<String>,
    title: Title,
) -> Result<Task> {
    let mut title = if let Some(title) = title.title {
        title
    } else if let Some(title) = title.title_simple {
        title.join(" ")
    } else {
        "".to_string()
    };
    // If no body was explicitly provided and the title contains newlines,
    // treat the first line as the title and the rest as the body (like git commit -m)
    let mut body = if body.is_none() {
        if let Some((first_line, rest)) = title.split_once('\n') {
            let extracted_body = rest.to_string();
            title = first_line.to_string();
            extracted_body
        } else {
            String::new()
        }
    } else {
        // Body was explicitly provided, so strip any newlines from title
        title = title.replace(['\n', '\r'], " ");
        body.unwrap_or_default()
    };
    if body == "-" {
        // add newline so you can type directly in the shell
        //eprintln!("");
        body.clear();
        std::io::stdin().read_to_string(&mut body)?;
    }
    if edit {
        let new_content = open_editor(format!("{title}\n\n{body}"))?;
        if let Some(content) = new_content.split_once("\n") {
            title = content.0.to_string();
            body = content.1.to_string();
        }
    }
    // Ensure title never contains newlines (invariant for index file format)
    title = title.replace(['\n', '\r'], " ");
    let task = workspace.new_task(title, body)?;
    workspace.handle_metadata(&task, None)?;
    Ok(task)
}

fn command_push(dir: PathBuf, edit: bool, body: Option<String>, title: Title) -> Result<()> {
    let mut workspace = Workspace::from_path(dir)?;
    let task = create_task(&mut workspace, edit, body, title)?;
    workspace.push_task(task)
}

fn command_append(dir: PathBuf, edit: bool, body: Option<String>, title: Title) -> Result<()> {
    let mut workspace = Workspace::from_path(dir)?;
    let task = create_task(&mut workspace, edit, body, title)?;
    workspace.append_task(task)
}

fn command_list(dir: PathBuf, all: bool, count: usize) -> Result<()> {
    let workspace = Workspace::from_path(dir)?;
    let stack = workspace.read_stack()?;

    if stack.empty() {
        println!("*No tasks*");
        exit(0);
    }

    for (_, stack_item) in stack
        .into_iter()
        .enumerate()
        .take_while(|(idx, _)| all || idx < &count)
    {
        if let Some(parsed) = task::parse(&stack_item.title) {
            println!("{}\t{}", stack_item.id, parsed.content.trim());
        } else {
            println!("{stack_item}");
        }
    }
    Ok(())
}

fn command_swap(dir: PathBuf) -> Result<()> {
    let workspace = Workspace::from_path(dir)?;
    workspace.swap_top()?;
    Ok(())
}

fn command_edit(dir: PathBuf, id: TaskId) -> Result<()> {
    let workspace = Workspace::from_path(dir)?;
    let id: TaskIdentifier = id.into();
    let mut task = workspace.task(id)?;
    let pre_links = task::parse(&task.to_string()).map(|pt| pt.intenal_links());
    let new_content = open_editor(format!("{}\n\n{}", task.title.trim(), task.body.trim()))?;
    if let Some((title, body)) = new_content.split_once("\n") {
        // Ensure title never contains newlines (invariant for index file format)
        task.title = title.replace(['\n', '\r'], " ");
        task.body = body.to_string();
        workspace.handle_metadata(&task, pre_links)?;
        task.save()?;
    }
    Ok(())
}

fn command_completion(shell: Shell) -> Result<()> {
    generate(shell, &mut Cli::command(), "tsk", &mut io::stdout());
    Ok(())
}

fn command_drop(dir: PathBuf, task_id: TaskId) -> Result<()> {
    if let Some(id) = Workspace::from_path(dir)?.drop(task_id.into())? {
        eprint!("Dropped ");
        println!("{id}");
    } else {
        eprintln!("No task to drop.");
        exit(1);
    }
    Ok(())
}

fn command_find(dir: PathBuf, short_id: bool, find_args: FindArgs) -> Result<()> {
    let id = Workspace::from_path(dir)?.search(None, !find_args.exclude_body, false)?;
    if let Some(id) = id {
        if short_id {
            // print as integer
            println!("{}", id.0);
        } else {
            println!("{id}");
        }
    } else {
        eprintln!("No task selected.");
        exit(1);
    }
    Ok(())
}

fn command_prioritize(dir: PathBuf, task_id: TaskId) -> Result<()> {
    Workspace::from_path(dir)?.prioritize(task_id.into())
}

fn command_deprioritize(dir: PathBuf, task_id: TaskId) -> Result<()> {
    Workspace::from_path(dir)?.deprioritize(task_id.into())
}

fn command_show(dir: PathBuf, task_id: TaskId, show_attrs: bool, raw: bool) -> Result<()> {
    let task = Workspace::from_path(dir)?.task(task_id.into())?;
    // YAML front-matter style. YAML is gross, but it's what everyone uses!
    if show_attrs && !task.attributes.is_empty() {
        println!("---");
        for (attr, value) in task.attributes.iter() {
            println!("{attr}: \"{value}\"");
        }
        println!("---");
    }
    match task::parse(&task.to_string()) {
        Some(styled_task) if !raw => {
            writeln!(io::stdout(), "{}", styled_task.content)?;
        }
        _ => {
            println!("{task}");
        }
    }
    Ok(())
}

fn command_follow(dir: PathBuf, task_id: TaskId, link_index: usize, edit: bool) -> Result<()> {
    let task = Workspace::from_path(dir.clone())?.task(task_id.into())?;
    if let Some(parsed_task) = task::parse(&task.to_string()) {
        if link_index == 0 || link_index > parsed_task.links.len() {
            eprintln!("Link index out of bounds.");
            exit(1);
        }
        let link = &parsed_task.links[link_index - 1];
        match link {
            ParsedLink::External(url) => {
                open::that_detached(url.as_str())?;
                Ok(())
            }
            ParsedLink::Internal(id) => {
                let taskid = taskid_from_tsk_id(*id);
                if edit {
                    command_edit(dir, taskid)
                } else {
                    command_show(dir, taskid, false, false)
                }
            }
        }
    } else {
        eprintln!("Unable to parse any links from body.");
        exit(1);
    }
}