use super::rune::Rune;
use super::stanza::Stanza;
use super::word::Word;
use crate::poem::Poem;
use std::path::Path;

/// A [Stanza] and it's [meter](Rune)
///
/// In addition to a [Stanza] and a [meter](Rune), this also holds a [bool]
/// value called `couplet`, indicating that it needs to accept input on `STDIN`
/// from the previous [Verse].
#[derive(Debug, Clone)]
pub struct Verse {
    pub stanza: Stanza,
    pub couplet: bool,
    pub io: Rune,
    pub poems: Vec<Poem>,
    pub meter: Rune,
}

impl Verse {
    /// Create a new [Verse]
    ///
    /// Returns a new [Verse], with an empty [Stanza], a meter of [Rune::None],
    /// and `couplet` set to `false`.
    pub fn new() -> Self {
        Verse {
            stanza: Stanza::new(),
            couplet: false,
            io: Rune::None,
            poems: Vec::new(),
            meter: Rune::None,
        }
    }

    /// Get the [Verse]'s verb
    ///
    /// Return the program to be forked
    pub fn verb(&self) -> String {
        self.stanza[0].clone()
    }

    /// Get the [Verse]'s clause
    ///
    /// Return program arguments, if they exist
    pub fn clause(&self) -> Option<Vec<String>> {
        match self.stanza.len() {
            0 => None,
            1 => None,
            _ => Some(self.stanza[1..].to_vec()),
        }
    }

    /// Alias to [Verse].stanza.push()
    pub fn push(&mut self, word: String) {
        self.stanza.push(word);
    }

    /// Alias to [Verse].stanza.is_empty()
    pub fn is_empty(&self) -> bool {
        self.stanza.is_empty()
    }

    /// Alias to [Verse].stanza.clear()
    pub fn clear(&mut self) {
        self.stanza.clear();
    }

    /// Check if the [Verse] contains any internal poems
    pub fn poems(&self) -> bool {
        if self.poems.len() > 0 {
            return true;
        }
        false
    }

    /// Push a word to the [Verse]'s [Stanza]
    ///
    /// Push a word to the [Stanza] after performing a few extra checks, such
    /// as whether or not the word is empty, or if the word should be
    /// interpreted as an environment variable.
    pub fn add(&mut self, word: &mut Word) {
        if !word.is_empty() {
            // Push the word, and clear the stack
            self.push(word.iter().collect());
            word.clear();
        }
    }

    /// Split a [Verse] into two different [Verse]s
    ///
    /// This is useful for [Rune::Read], [Rune::Write], and [Rune::Addendum].
    pub fn split(&mut self, c: &str) -> Vec<String> {
        for (i, s) in self.stanza.iter().enumerate() {
            if *s == c {
                let split = self.stanza.split_off(i);
                return split[1..].to_vec();
            }
        }
        vec![]
    }

    /// Check if the `verb()` exists in the `$PATH`
    ///
    /// First checks if the `verb()` is a relative or full path. If it is,
    /// check whether or not it exists. If it does exist, return true,
    /// otherwise seeif the `verb()` is cached in our list of binaries. Search is
    /// done in $PATH order.
    ///
    /// # Examples
    /// ```
    /// let bins = vec!["cargo", "ruby", "cat"]
    ///            .into_iter()
    ///            .map(String::from)
    ///            .collect<Vec<String>>();
    ///
    /// let command_success = vec!["cargo", "build", "--release"]
    ///                       .into_iter()
    ///                       .map(String::from)
    ///                       .collect<Vec<String>>();
    ///
    /// let command_fail = vec!["make", "-j8"]
    ///                    .into_iter()
    ///                    .map(String::from)
    ///                    .collect<Vec<String>>();
    ///
    /// let stanza_success = Stanza::new(command_success);
    /// let stanza_fail = Stanza::new(command_fail);
    ///
    /// stanza_success.spellcheck(bins) // -> true
    /// stanza_fail.spellcheck(bins) // -> false
    /// ```
    pub fn spellcheck(&self, bins: &Vec<String>) -> bool {
        // An empty verb (i.e. the empty string) cannot be a program, so
        // return false
        // Thanks to the parsing in Poem::read, however, it's
        // unlikely for this to happen
        if self.verb().is_empty() {
            return false;
        }

        // Only search the $PATH if a full or relative path was not given, or
        // if the path given does not exist
        if !Path::new(self.verb().as_str()).exists() {
            // Try to find a binary in our path with the same name as the verb
            // Searches in $PATH order
            match bins
                .iter()
                .find(|bin| bin.split('/').last().unwrap() == self.verb())
            {
                Some(_) => return true,
                None => return false,
            }
        }

        // Return true if the full path or relative path exists
        true
    }
}