use std::error::Error;
use std::fmt;
use std::fs::{metadata, File};
use std::io::copy;
use std::marker::PhantomData;
use std::path::Path;

use crate::resources::Resource;
use crate::symbols::{Action, OwnedSymbolAction, Symbol, SymbolAction, SymbolRunner};

pub struct Concat<S, D, I> {
  target: D,
  sources: S,
  source_item: PhantomData<I>,
}

impl<S, D, I> Concat<S, D, I> {
  pub fn new(sources: S, target: D) -> Self {
    Self {
      target,
      sources,
      source_item: PhantomData::default(),
    }
  }
}

impl<S: AsRef<[I]>, D: AsRef<Path>, I: AsRef<Path>> Symbol for Concat<S, D, I> {
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    let target = self.target.as_ref();
    if !target.exists() {
      return Ok(false);
    }
    let target_date = metadata(target)?.modified()?;
    for source in self.sources.as_ref() {
      if metadata(source)?.modified()? > target_date {
        return Ok(false);
      }
    }
    Ok(true)
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    let mut file = File::create(self.target.as_ref())?;
    for source in self.sources.as_ref() {
      copy(&mut File::open(source)?, &mut file)?;
    }
    Ok(())
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    let mut r: Vec<Resource> = self
      .sources
      .as_ref()
      .iter()
      .map(|s| Resource::new("file", s.as_ref().to_str().unwrap()))
      .collect();
    if let Some(parent) = self.target.as_ref().parent() {
      r.push(Resource::new("dir", parent.to_str().unwrap()))
    }
    r
  }

  fn as_action<'a>(&'a self, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a> {
    Box::new(SymbolAction::new(runner, self))
  }

  fn into_action<'a>(self: Box<Self>, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a>
  where
    Self: 'a,
  {
    Box::new(OwnedSymbolAction::new(runner, *self))
  }
}

impl<S, D: AsRef<Path>, I> fmt::Display for Concat<S, D, I> {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
    write!(f, "Concat {}", self.target.as_ref().display())
  }
}