//! Utils related to asking [Y/n] questions to the user.
//!
//! Example:
//!   "Do you want to overwrite 'archive.tar.gz'? [Y/n]"

use std::{
    borrow::Cow,
    io::{stdin, BufRead, IsTerminal},
    path::Path,
};

use fs_err as fs;

use super::{strip_cur_dir, to_utf};
use crate::{
    accessible::is_running_in_accessible_mode,
    error::{Error, FinalError, Result},
    utils::{self, colors, io::lock_and_flush_output_stdio},
};

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
/// Determines if overwrite questions should be skipped or asked to the user
pub enum QuestionPolicy {
    /// Ask the user every time
    Ask,
    /// Set by `--yes`, will say 'Y' to all overwrite questions
    AlwaysYes,
    /// Set by `--no`, will say 'N' to all overwrite questions
    AlwaysNo,
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
/// Determines which action is being questioned
pub enum QuestionAction {
    /// question called from a compression function
    Compression,
    /// question called from a decompression function
    Decompression,
}

/// Check if QuestionPolicy flags were set, otherwise, ask user if they want to overwrite.
pub fn user_wants_to_overwrite(path: &Path, question_policy: QuestionPolicy) -> crate::Result<bool> {
    match question_policy {
        QuestionPolicy::AlwaysYes => Ok(true),
        QuestionPolicy::AlwaysNo => Ok(false),
        QuestionPolicy::Ask => {
            let path = to_utf(strip_cur_dir(path));
            let path = Some(&*path);
            let placeholder = Some("FILE");
            Confirmation::new("Do you want to overwrite 'FILE'?", placeholder).ask(path)
        }
    }
}

/// Create the file if it doesn't exist and if it does then ask to overwrite it.
/// If the user doesn't want to overwrite then we return [`Ok(None)`]
pub fn ask_to_create_file(path: &Path, question_policy: QuestionPolicy) -> Result<Option<fs::File>> {
    match fs::OpenOptions::new().write(true).create_new(true).open(path) {
        Ok(w) => Ok(Some(w)),
        Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {
            if user_wants_to_overwrite(path, question_policy)? {
                utils::remove_file_or_dir(path)?;
                Ok(Some(fs::File::create(path)?))
            } else {
                Ok(None)
            }
        }
        Err(e) => Err(Error::from(e)),
    }
}

/// Check if QuestionPolicy flags were set, otherwise, ask the user if they want to continue.
pub fn user_wants_to_continue(
    path: &Path,
    question_policy: QuestionPolicy,
    question_action: QuestionAction,
) -> crate::Result<bool> {
    match question_policy {
        QuestionPolicy::AlwaysYes => Ok(true),
        QuestionPolicy::AlwaysNo => Ok(false),
        QuestionPolicy::Ask => {
            let action = match question_action {
                QuestionAction::Compression => "compress",
                QuestionAction::Decompression => "decompress",
            };
            let path = to_utf(strip_cur_dir(path));
            let path = Some(&*path);
            let placeholder = Some("FILE");
            Confirmation::new(&format!("Do you want to {action} 'FILE'?"), placeholder).ask(path)
        }
    }
}

/// Confirmation dialog for end user with [Y/n] question.
///
/// If the placeholder is found in the prompt text, it will be replaced to form the final message.
pub struct Confirmation<'a> {
    /// The message to be displayed with the placeholder text in it.
    /// e.g.: "Do you want to overwrite 'FILE'?"
    pub prompt: &'a str,

    /// The placeholder text that will be replaced in the `ask` function:
    /// e.g.: Some("FILE")
    pub placeholder: Option<&'a str>,
}

impl<'a> Confirmation<'a> {
    /// Creates a new Confirmation.
    pub const fn new(prompt: &'a str, pattern: Option<&'a str>) -> Self {
        Self {
            prompt,
            placeholder: pattern,
        }
    }

    /// Creates user message and receives a boolean input to be used on the program
    pub fn ask(&self, substitute: Option<&'a str>) -> crate::Result<bool> {
        let message = match (self.placeholder, substitute) {
            (None, _) => Cow::Borrowed(self.prompt),
            (Some(_), None) => unreachable!("dev error, should be reported, we checked this won't happen"),
            (Some(placeholder), Some(subs)) => Cow::Owned(self.prompt.replace(placeholder, subs)),
        };

        if !stdin().is_terminal() {
            eprintln!("{}", message);
            eprintln!("Pass --yes to proceed");
            return Ok(false);
        }

        let _locks = lock_and_flush_output_stdio()?;
        let mut stdin_lock = stdin().lock();

        // Ask the same question to end while no valid answers are given
        loop {
            if is_running_in_accessible_mode() {
                eprintln!(
                    "{} {}yes{}/{}no{}: ",
                    message,
                    *colors::GREEN,
                    *colors::RESET,
                    *colors::RED,
                    *colors::RESET
                );
            } else {
                eprintln!(
                    "{} [{}Y{}/{}n{}] ",
                    message,
                    *colors::GREEN,
                    *colors::RESET,
                    *colors::RED,
                    *colors::RESET
                );
            }

            let mut answer = String::new();
            let bytes_read = stdin_lock.read_line(&mut answer)?;

            if bytes_read == 0 {
                let error = FinalError::with_title("Unexpected EOF when asking question.")
                    .detail("When asking the user:")
                    .detail(format!("  \"{message}\""))
                    .detail("Expected 'y' or 'n' as answer, but found EOF instead.")
                    .hint("If using Ouch in scripting, consider using `--yes` and `--no`.");

                return Err(error.into());
            }

            answer.make_ascii_lowercase();
            match answer.trim() {
                "" | "y" | "yes" => return Ok(true),
                "n" | "no" => return Ok(false),
                _ => continue, // Try again
            }
        }
    }
}