#[cfg(feature = "mkl")]
extern crate intel_mkl_src;

#[cfg(feature = "accelerate")]
extern crate accelerate_src;

use anyhow::Error as E;
use clap::{Parser, ValueEnum};

use candle::{DType, Tensor};
use candle_nn::VarBuilder;
use candle_transformers::models::marian;

use tokenizers::Tokenizer;

#[derive(Clone, Debug, Copy, ValueEnum)]
enum Which {
    Base,
    Big,
}

// TODO: Maybe add support for the conditional prompt.
#[derive(Parser)]
struct Args {
    #[arg(long)]
    model: Option<String>,

    #[arg(long)]
    tokenizer: Option<String>,

    #[arg(long)]
    tokenizer_dec: Option<String>,

    /// Choose the variant of the model to run.
    #[arg(long, default_value = "big")]
    which: Which,

    /// Run on CPU rather than on GPU.
    #[arg(long)]
    cpu: bool,

    /// Use the quantized version of the model.
    #[arg(long)]
    quantized: bool,

    /// Text to be translated
    #[arg(long)]
    text: String,
}

pub fn main() -> anyhow::Result<()> {
    use hf_hub::api::sync::Api;
    let args = Args::parse();

    let config = match args.which {
        Which::Base => marian::Config::opus_mt_fr_en(),
        Which::Big => marian::Config::opus_mt_tc_big_fr_en(),
    };
    let tokenizer = {
        let tokenizer = match args.tokenizer {
            Some(tokenizer) => std::path::PathBuf::from(tokenizer),
            None => {
                let name = match args.which {
                    Which::Base => "tokenizer-marian-base-fr.json",
                    Which::Big => "tokenizer-marian-fr.json",
                };
                Api::new()?
                    .model("lmz/candle-marian".to_string())
                    .get(name)?
            }
        };
        Tokenizer::from_file(&tokenizer).map_err(E::msg)?
    };

    let tokenizer_dec = {
        let tokenizer = match args.tokenizer_dec {
            Some(tokenizer) => std::path::PathBuf::from(tokenizer),
            None => {
                let name = match args.which {
                    Which::Base => "tokenizer-marian-base-en.json",
                    Which::Big => "tokenizer-marian-en.json",
                };
                Api::new()?
                    .model("lmz/candle-marian".to_string())
                    .get(name)?
            }
        };
        Tokenizer::from_file(&tokenizer).map_err(E::msg)?
    };

    let device = candle_examples::device(args.cpu)?;
    let vb = {
        let model = match args.model {
            Some(model) => std::path::PathBuf::from(model),
            None => match args.which {
                Which::Base => Api::new()?
                    .repo(hf_hub::Repo::with_revision(
                        "Helsinki-NLP/opus-mt-fr-en".to_string(),
                        hf_hub::RepoType::Model,
                        "refs/pr/4".to_string(),
                    ))
                    .get("model.safetensors")?,
                Which::Big => Api::new()?
                    .model("Helsinki-NLP/opus-mt-tc-big-fr-en".to_string())
                    .get("model.safetensors")?,
            },
        };
        unsafe { VarBuilder::from_mmaped_safetensors(&[&model], DType::F32, &device)? }
    };
    let model = marian::MTModel::new(&config, vb)?;

    let mut logits_processor =
        candle_transformers::generation::LogitsProcessor::new(1337, None, None);

    let encoder_xs = {
        let mut tokens = tokenizer
            .encode(args.text, true)
            .map_err(E::msg)?
            .get_ids()
            .to_vec();
        tokens.push(config.eos_token_id);
        let tokens = Tensor::new(tokens.as_slice(), &device)?.unsqueeze(0)?;
        model.encoder().forward(&tokens, 0)?
    };

    let mut token_ids = vec![config.decoder_start_token_id];
    for index in 0..1000 {
        // TODO: Add a kv cache.
        let context_size = if index >= 1000 { 1 } else { token_ids.len() };
        let start_pos = token_ids.len().saturating_sub(context_size);
        let input_ids = Tensor::new(&token_ids[start_pos..], &device)?.unsqueeze(0)?;
        let logits = model.decode(&input_ids, &encoder_xs)?;
        let logits = logits.squeeze(0)?;
        let logits = logits.get(logits.dim(0)? - 1)?;
        let token = logits_processor.sample(&logits)?;
        token_ids.push(token);
        println!("{token}");
        if token == config.eos_token_id || token == config.forced_eos_token_id {
            break;
        }
    }
    println!(
        "{}",
        tokenizer_dec.decode(&token_ids, true).map_err(E::msg)?
    );
    Ok(())
}