use blake2::{Blake2b, Digest};
use chrono;
use chrono::offset::TimeZone;
use chrono::Date;
use chrono::NaiveDate;
use chrono::Utc;
use failure::Fallible;
use image_utils;
use markdown;
use percent_encoding::{utf8_percent_encode, DEFAULT_ENCODE_SET};
use rss::{Channel, ChannelBuilder, Guid, ItemBuilder};
use std::env;
use std::fs;
use std::fs::DirEntry;
use std::fs::File;
use std::fs::OpenOptions;
use std::io;
use std::io::prelude::*;
use std::path::{Path, PathBuf};

use base64;
use std::collections::HashMap;

mod hash_dict;

#[derive(Debug)]
struct BreadRendered {
    thumb: String,
    detail: String,
    rss_item: Option<rss::Item>,
    title: String,
    url: String,
    detail_fname: String,
}

#[derive(Debug)]
struct Bread {
    path: PathBuf,
    rel_path: PathBuf,
    date: chrono::NaiveDate,
    note: String,
    rss_note: String,
    images: Vec<PathBuf>,
    rendered: BreadRendered,
}

//impl From<std::option::NoneError> for failure::Error {
//    fn from(x: std::option::NoneError) -> Self {
//        failure::err_msg("Expected something, found nothing.")
//    }
//}

#[derive(Debug)]
struct BreadLink {
    label: String,
    url: String,
}

impl Bread {
    fn compile(&mut self, config: &mut GalleryConfig, prev : Option<BreadLink>, next : Option<BreadLink>) -> Fallible<()> {
        let date = self.date.format("%Y/%m/%d").to_string();
        let date_slug = self.date.format("%Y-%m-%d").to_string();
        let detail_file = date_slug.clone() + ".html";
        println!("+ {}", date_slug);

        self.rendered.title = date.clone();
        self.rendered.detail_fname = detail_file.clone();

        // figure out the thumbnail pic
        let (img_path, img_alt) = {
            let mut first_img: &PathBuf = self.images.get(0).expect(&format!("No images for bread {}", date_slug));
            for im in &self.images {
                if im.file_name().unwrap().to_str().unwrap().contains("cover") {
                    first_img = im;
                    break;
                }
            }
            (
                first_img.to_str().unwrap().to_owned(),
                first_img.file_name().unwrap().to_str().unwrap().to_owned(),
            )
        };

        let note = if self.note.is_empty() {
            "<i>There's no note about this bread.</i>"
        } else {
            &self.note
        };

        let thumb_fname = date_slug.clone() + "." + Path::new(&img_path).extension().unwrap().to_str().unwrap();
        let thumb_path = config.thumbs_path.join(&thumb_fname);
        let thumb_relpath = thumb_path.strip_prefix(&config.web_path)?;

        let image_path_encoded =
            utf8_percent_encode(thumb_relpath.to_str().unwrap(), DEFAULT_ENCODE_SET).to_string();

        let image_real_path = config.web_path.join(img_path);

        // Create the thumb
        {
            let mut img_file = fs::File::open(&image_real_path)?;
            let mut hasher = Blake2b::new();
            io::copy(&mut img_file, &mut hasher)?;
            let hash = base64::encode(&hasher.result());

            let hash_key = thumb_path.to_str().unwrap();
            let old_hash = config.image_hashes.get(hash_key);
            if old_hash.is_none() || !old_hash.unwrap().eq(&hash) {
                println!("building thumb...");

                let im = image::open(&image_real_path)?;
                let im = im.thumbnail(500, 500);
                im.save(&thumb_path)?;

                config.image_hashes.put(hash_key.to_string(), hash);
            }
        }

        // Prepare the thumb card for the gallery page
        {
            self.rendered.thumb = config
                .template("_thumb.html")?
                .replace("{detail_url}", &detail_file)
                .replace("{img_src}", &image_path_encoded)
                .replace("{img_alt}", &img_alt)
                .replace("{title}", &date);
        }

        // Add to RSS
        {
            let image_url: String = config.base_url.to_owned() + "/" + &image_path_encoded;

            let link: String = config.base_url.to_owned() + "/" + &detail_file;
            let mut guid = Guid::default();
            guid.set_value(link.clone());
            guid.set_permalink(true);

            let date_formatted: Date<Utc> = chrono::Utc.from_local_date(&self.date).unwrap();
            let dt = date_formatted.and_hms(12, 0, 0);

            let mut descr = String::new();
            if !self.rss_note.is_empty() {
                descr.push_str(&self.rss_note);
                descr.push_str("<hr>");
            }
            descr.push_str(note);
            descr.push_str(&format!(
                "<img src=\"{}\" alt=\"{}\"><p><i>Open the link for full-res photos ({} total)</i>",
                image_url,
                img_alt,
                self.images.len()
            ));

            self.rendered.url = link.clone();

            let item: rss::Item = ItemBuilder::default()
                .title(date.clone())
                .link(link)
                .description(descr)
                .guid(guid)
                .pub_date(dt.to_rfc2822())
                .build().unwrap();

            self.rendered.rss_item = Some(item);
        }

        let head_tpl = config.template("_head.html")?;

        // Generate the detail page
        {
            let win_title = format!("Bread from {}", date);

            let detail = config
                .template("detail.html")?
                .replace("{head}", &head_tpl.replace("{title}", &win_title))
                .replace("{title}", &win_title)
                .replace("{date}", &date_slug)
                .replace("{url}", &format!("{}/{}", config.base_url, detail_file))
                .replace(
                    "{thumb_url}",
                    &format!("{}/thumbs/{}", config.base_url, thumb_fname),
                )
                .replace("{heading}", &date)
                .replace("{prev}", &(match prev {
                    Some(b) => format!("<a class=\"prev\" href=\"{}\" title=\"{}\">&lt;</a>", b.url, b.label),
                    None => "".to_string()
                }))
                .replace("{next}", &(match next {
                    Some(b) => format!("<a class=\"next\" href=\"{}\" title=\"{}\">&gt;</a>", b.url, b.label),
                    None => "".to_string()
                }))
                .replace("{note}", note.trim());

            let mut pics = String::new();
            for img in &self.images {
                pics.push_str(&format!(
                    "      <a href=\"{src}\"><img src=\"{src}\"></a>\n",
                    src = &utf8_percent_encode(img.to_str().unwrap(), DEFAULT_ENCODE_SET).to_string()
                ))
            }

            let detail = detail.replace("{images}", &pics.trim());

            let mut f = OpenOptions::new().write(true).truncate(true).create(true).open(config.web_path.join(detail_file)).unwrap();
            f.write(detail.as_bytes()).unwrap();

            self.rendered.detail = detail;
        }

        Ok(())
    }

    fn to_link(&self) -> BreadLink {
        BreadLink {
            label: self.date.format("%Y/%m/%d").to_string(),
            url: self.date.format("%Y-%m-%d.html").to_string(),
        }
    }

    fn parse(base_dir: &PathBuf, bread_dir: &DirEntry) -> Result<Bread, std::io::Error> {
        let bpath = bread_dir.path();
        let mut note = String::new();
        let mut rss_note = String::new();

        let mut note_path = bpath.join("note.txt");
        let mut rss_note_path = bpath.join("rss.txt");

        // try a md one as a fallback
        if !note_path.exists() {
            note_path = bpath.join("note.md");
        }

        if !rss_note_path.exists() {
            rss_note_path = bpath.join("rss.md");
        }

        if note_path.exists() {
            let mut note_file = File::open(note_path)?;
            note_file.read_to_string(&mut note)?;
            note = markdown::to_html(&note);
        }

        if rss_note_path.exists() {
            let mut note_file = File::open(rss_note_path)?;
            note_file.read_to_string(&mut rss_note)?;
            rss_note = markdown::to_html(&rss_note);
        }

        let mut bread_files: Vec<DirEntry> = fs::read_dir(&bpath)?.map(|e| e.unwrap()).collect();
        bread_files.sort_by(|x, y| x.file_name().cmp(&y.file_name()));

        let images = bread_files
            .iter()
            .filter(|&f| {
                let fname = f.file_name();
                let name = fname.to_str().unwrap();
                return name.ends_with(".png")
                    || name.ends_with(".jpg")
                    || name.ends_with(".jpeg")
                    || name.ends_with(".gif");
            })
            .map(|x| x.path().strip_prefix(base_dir).unwrap().to_path_buf())
            .collect();

        return Ok(Bread {
            date: NaiveDate::parse_from_str(
                bpath.file_name().unwrap().to_str().unwrap(),
                "%Y-%m-%d",
            )
            .unwrap(),
            rel_path: bpath.strip_prefix(base_dir).unwrap().to_path_buf(),
            path: bpath,
            note,
            rss_note,
            images,
            rendered: BreadRendered {
                thumb: "".to_string(),
                detail: "".to_string(),
                rss_item: None,
                title: "".to_string(),
                url: "".to_string(),
                detail_fname: "".to_string()
            },
        });
    }
}

struct GalleryConfig {
    web_path: PathBuf,
    data_path: PathBuf,
    tpl_path: PathBuf,
    thumbs_path: PathBuf,
    base_url: String,
    templates: HashMap<String, String>,
    image_hashes: hash_dict::HashDict,
}

impl GalleryConfig {
    fn template(&mut self, name: &str) -> Fallible<String> {
        if let Some(text) = self.templates.get(name) {
            return Ok(text.clone());
        }

        let mut tpl = String::new();
        File::open(self.tpl_path.join(name))?.read_to_string(&mut tpl)?;
        self.templates.insert(name.to_string(), tpl.clone());
        Ok(tpl)
    }
}

fn main() -> Fallible<()> {

    let mut config = {
        let cwd = env::current_dir().unwrap();
        let web_path = cwd.join("web");
        let data_path = web_path.join("data");
        let tpl_path = web_path.join("templates");
        let thumbs_path = web_path.join("thumbs");

        GalleryConfig {
            web_path,
            data_path,
            tpl_path,
            thumbs_path,
            base_url: "https://www.ondrovo.com/bread".into(),
            templates: HashMap::new(),
            image_hashes: hash_dict::HashDict::load(cwd.join(".hashes.txt"))?,
        }
    };

    let mut bread_dirs: Vec<DirEntry> = fs::read_dir(&config.data_path)?.filter_map(|e| e.ok()).collect();
    bread_dirs.sort_by(|x, y| x.file_name().cmp(&y.file_name()));

    let mut breads: Vec<Bread> = bread_dirs
        .iter()
        .filter_map(|p| Bread::parse(&config.web_path, &p).ok())
        .collect();

    for i in 0..breads.len() {
        let preceding = if i <= 0 { None } else {
            match breads.get(i - 1) {
                Some(b) => Some(b.to_link()),
                None => None
            }
        };

        let following = match breads.get(i + 1) {
            Some(b) => Some(b.to_link()),
            None => None
        };

        let cur = breads.get_mut(i).unwrap();

        cur.compile(&mut config, preceding, following)?;
    }

    let mut channel: Channel = ChannelBuilder::default()
        .title("Piggo's Bread Gallery")
        .link("https://www.ondrovo.com/bread")
        .description("Sourdough feed")
        .build()
        .unwrap();

    config.image_hashes.save();

    let mut start = breads.len() as i32 - 10;
    if start < 0 {
        start = 0;
    }

    // rss
    {
        let mut channel_items = vec![];
        for b in &breads[start as usize..] {
            channel_items.push(b.rendered.rss_item.clone().unwrap());
        }

        println!("Generating feed...");
        let f = OpenOptions::new().write(true).truncate(true).create(true).open(config.web_path.join("feed.xml")).unwrap();
        channel.set_items(channel_items);
        channel.pretty_write_to(f, b' ', 2).unwrap();
    }

    // main page
    {
        // make thumbs go from the newest to the oldest
        breads.reverse();

        let mut thumbs_buf = String::new();
        for b in &breads {
            thumbs_buf.push_str(&b.rendered.thumb);
        }

        println!("Building the gallery page");
        let main = config.template("index.html")?.replace("{breads}", &thumbs_buf.trim())
            .replace("{head}", config.template("_head.html")?.replace("{title}", "Piggo's breads").trim());

        let mut f = OpenOptions::new().write(true).truncate(true).create(true).open(config.web_path.join("index.html")).unwrap();
        f.write(main.as_bytes()).unwrap();
    }

    Ok(())
}