use std::fs::{self, File};
use std::path::PathBuf;
use std::io::Write;
use toml;

use config::Config;
use super::MDBook;
use theme;
use errors::*;


/// A helper for setting up a new book and its directory structure.
#[derive(Debug, Clone, PartialEq)]
pub struct BookBuilder {
    root: PathBuf,
    create_gitignore: bool,
    config: Config,
    copy_theme: bool,
}

impl BookBuilder {
    pub fn new<P: Into<PathBuf>>(root: P) -> BookBuilder {
        BookBuilder {
            root: root.into(),
            create_gitignore: false,
            config: Config::default(),
            copy_theme: false,
        }
    }

    /// Set the `Config` to be used.
    pub fn with_config(&mut self, cfg: Config) -> &mut BookBuilder {
        self.config = cfg;
        self
    }

    pub fn copy_theme(&mut self, copy: bool) -> &mut BookBuilder {
        self.copy_theme = copy;
        self
    }

    pub fn create_gitignore(&mut self, create: bool) -> &mut BookBuilder {
        self.create_gitignore = create;
        self
    }

    pub fn config(&self) -> &Config {
        &self.config
    }

    pub fn build(&self) -> Result<MDBook> {
        info!("Creating a new book with stub content");

        self.create_directory_structure()
            .chain_err(|| "Unable to create directory structure")?;

        self.create_stub_files()
            .chain_err(|| "Unable to create stub files")?;

        if self.create_gitignore {
            self.build_gitignore()
                .chain_err(|| "Unable to create .gitignore")?;
        }

        if self.copy_theme {
            self.copy_across_theme()
                .chain_err(|| "Unable to copy across the theme")?;
        }

        self.write_book_toml()?;

        let book = MDBook::load(&self.root)
            .expect("The BookBuilder should always create a valid book. \
            If you are seeing this it is a bug and should be reported.");

        Ok(book)
    }

    fn write_book_toml(&self) -> Result<()> {
        debug!("[*] Writing book.toml");
        let book_toml = self.root.join("book.toml");
        let cfg = toml::to_vec(&self.config)
            .chain_err(|| "Unable to serialize the config")?;

        File::create(book_toml)
            .chain_err(|| "Couldn't create book.toml")?
            .write_all(&cfg)
            .chain_err(|| "Unable to write config to book.toml")?;
        Ok(())
    }

    fn copy_across_theme(&self) -> Result<()> {
        debug!("[*] Copying theme");

        let themedir = self.config.html_config()
            .and_then(|html| html.theme)
            .unwrap_or_else(|| self.config.book.src.join("theme"));
        let themedir = self.root.join(themedir);

        if !themedir.exists() {
            debug!("[*]: {:?} does not exist, creating the directory",
            themedir);         fs::create_dir(&themedir)?;
        }

        let mut index = File::create(themedir.join("index.hbs"))?;
        index.write_all(theme::INDEX)?;

        let mut css = File::create(themedir.join("book.css"))?;
        css.write_all(theme::CSS)?;

        let mut favicon = File::create(themedir.join("favicon.png"))?;
        favicon.write_all(theme::FAVICON)?;

        let mut js = File::create(themedir.join("book.js"))?;
        js.write_all(theme::JS)?;

        let mut highlight_css = File::create(themedir.join("highlight.css"))?;
        highlight_css.write_all(theme::HIGHLIGHT_CSS)?;

        let mut highlight_js = File::create(themedir.join("highlight.js"))?;
        highlight_js.write_all(theme::HIGHLIGHT_JS)?;

        Ok(())
    }

    fn build_gitignore(&self) -> Result<()> {
        debug!("[*]: Creating .gitignore");

        Ok(())
    }

    fn create_stub_files(&self) -> Result<()> {
        debug!("[*] Creating example book contents");
        let src_dir = self.root.join(&self.config.book.src);

        let summary = src_dir.join("SUMMARY.md");
        let mut f = File::create(&summary).chain_err(|| "Unable to create SUMMARY.md")?;
        writeln!(f, "# Summary")?;
        writeln!(f, "")?;
        writeln!(f, "- [Chapter 1](./chapter_1.md)")?;

        let chapter_1 = src_dir.join("chapter_1.md");
        let mut f = File::create(&chapter_1).chain_err(|| "Unable to create chapter_1.md")?;
        writeln!(f, "# Chapter 1")?;

        Ok(())
    }

    fn create_directory_structure(&self) -> Result<()> {
        debug!("[*]: Creating directory tree");
        fs::create_dir_all(&self.root)?;

        let src = self.root.join(&self.config.book.src);
        fs::create_dir_all(&src)?;

        let build = self.root.join(&self.config.build.build_dir);
        fs::create_dir_all(&build)?;

        Ok(())
    }
}