use std::collections::BTreeMap;
use std::path::PathBuf;
use std::fs::File;
use std::io;

use rocksdb::{SstFileWriter, EnvOptions, ColumnFamilyOptions};
use raptor::{MetadataBuilder, DocIndex, Tokenizer};
use unidecode::unidecode;
use csv::ReaderBuilder;

use crate::common_words::{self, CommonWords};
use crate::index::csv_feature::CommandCsv;

#[derive(Debug, Deserialize)]
struct Product {
    #[serde(rename = "_unit_id")]
    id: u64,
    #[serde(rename = "product_title")]
    title: String,
    #[serde(rename = "product_image")]
    image: String,
    #[serde(rename = "product_description")]
    description: String,
}

#[derive(Debug)]
pub struct CsvIndexer {
    common_words: CommonWords,
    products: PathBuf,
}

impl CsvIndexer {
    pub fn from_command(command: CommandCsv) -> io::Result<CsvIndexer> {
        let common_words = common_words::from_file(command.stop_words)?;
        let products = command.products;

        Ok(CsvIndexer { common_words, products })
    }

    pub fn index(self) {
        let random_name = moby_name_gen::random_name();
        let map_file = format!("{}.map", random_name);
        let idx_file = format!("{}.idx", random_name);
        let sst_file = format!("{}.sst", random_name);

        let env_options = EnvOptions::new();
        let cf_options = ColumnFamilyOptions::new();
        let mut sst_file_writer = SstFileWriter::new(env_options, cf_options);
        sst_file_writer.open(&sst_file).expect("open the sst file");

        let map = File::create(&map_file).unwrap();
        let indexes = File::create(&idx_file).unwrap();
        let mut builder = MetadataBuilder::new(map, indexes);
        let mut fields = BTreeMap::new();

        let mut rdr = ReaderBuilder::new().from_path(&self.products).expect("reading product file");
        let mut errors = 0;

        for result in rdr.deserialize() {
            let product: Product = match result {
                Ok(product) => product,
                Err(e) => { eprintln!("{:?}", e); errors += 1; continue },
            };

            let title = Tokenizer::new(&product.title);
            let title = title.iter().filter(|&(_, w)| !self.common_words.contains(w));
            insert_document_words(&mut builder, product.id, 0, title);

            let description = Tokenizer::new(&product.description);
            let description = description.iter().filter(|&(_, w)| !self.common_words.contains(w));
            insert_document_words(&mut builder, product.id, 1, description);

            // TODO simplify this by using functions and
            //      use the MetadataBuilder internal BTreeMap ?
            let key = format!("{}-title", product.id);
            let value = product.title;
            fields.insert(key, value);

            let key = format!("{}-description", product.id);
            let value = product.description;
            fields.insert(key, value);

            let key = format!("{}-image", product.id);
            let value = product.image;
            fields.insert(key, value);
        }

        for (key, value) in fields {
            sst_file_writer.put(key.as_bytes(), value.as_bytes()).unwrap();
        }
        let _sst_file_info = sst_file_writer.finish().unwrap();

        builder.finish().unwrap();

        println!("Found {} errorneous lines", errors);
        println!("Succesfully created {:?} dump.", random_name);
    }
}

fn insert_document_words<'a, I, A, B>(builder: &mut MetadataBuilder<A, B>, doc_index: u64, attr: u8, words: I)
where A: io::Write,
      B: io::Write,
      I: IntoIterator<Item=(usize, &'a str)>,
{
    for (index, word) in words {
        let doc_index = DocIndex {
            document: doc_index,
            attribute: attr,
            attribute_index: index as u32,
        };
        // insert the exact representation
        let word_lower = word.to_lowercase();

        // and the unidecoded lowercased version
        let word_unidecoded = unidecode(word).to_lowercase();
        if word_lower != word_unidecoded {
            builder.insert(word_unidecoded, doc_index);
        }

        builder.insert(word_lower, doc_index);
    }
}