//! Convert between different sequence formats
//! # Examples
//! 
//! ## Simple conversion
//! ```bash
//! cat file.fastq | fasten_convert -i fastq -o fasta > out.fasta
//! ```
//! ## Convert to sam and then to bam
//! ```bash
//! cat file.fastq | fasten_convert -i fastq -o sam   | samtools view -bS > file.bam
//! ```
//! ## Convert to fastq and then clean
//! ```bash
//! cat file.fasta | fasten_convert -i fasta -o fastq | fasten_clean > cleaned.fastq
//!```

//! # Usage
//!```text
//!Usage: fasten_convert [-h] [-n INT] [-p] [-v] [-i FORMAT] [-o FORMAT]
//!
//!Options:
//!    -h, --help          Print this help menu.
//!    -n, --numcpus INT   Number of CPUs (default: 1)
//!    -p, --paired-end    The input reads are interleaved paired-end
//!    -v, --verbose       Print more status messages
//!    -i, --in-format FORMAT
//!                        The input format for stdin
//!    -o, --out-format FORMAT
//!                        The output format for stdin
//!  FORMAT can be: fastq, fasta, sam
//!```

extern crate getopts;
extern crate fasten;
extern crate fastq;
extern crate bam;

use bam::RecordReader;

use fasten::fasten_base_options;
use fasten::fasten_base_options_matches;
use fasten::logmsg;

use std::io::stdin;
use fastq::{Parser, Record};

use std::sync::mpsc::channel;

/// Struct that can handle paired end reads
#[derive(Debug, Clone)]
struct FastenSeq {
  id1:   String,
  seq1:  String,
  qual1: String,
  id2:   String,
  seq2:  String,
  qual2: String,
}
impl FastenSeq{
  /// a blank new object is a set of blank strings for each value
  fn new() -> FastenSeq{
    return FastenSeq{
      id1:   String::new(),
      seq1:  String::new(),
      qual1: String::new(),
      id2:   String::new(),
      seq2:  String::new(),
      qual2: String::new(),
    };
  }
  /// Return a formatted string as a fastq entry
  fn as_fastq(&self) -> String {
    let mut entry:String = format!("@{}\n{}\n+\n{}",
                             self.id1, self.seq1, self.qual1);
    if !self.id2.is_empty() {
      entry = format!("{}\n@{}\n{}\n+\n{}",
                entry, self.id2, self.seq2, self.qual2);
    }
    return entry;
  }

  /// Return a formatted string as a fasta entry
  fn as_fasta(&self) -> String {
    let mut entry:String = format!(">{}\n{}",
                             self.id1, self.seq1);
    if !self.id2.is_empty() {
      entry = format!("{}\n>{}\n{}",
                entry, self.id2, self.seq2);
    }
    return entry;
  }

  /// Return a formatted string as a sam entry
  fn as_sam(&self) -> String {
    let mut flag = "4"; // unmapped

    if !self.id2.is_empty() {
      flag = "77"; // unmapped + pair unmapped + has pair + first in pair
    }

    let mut entry:String = vec![self.id1.as_str(), flag, "*", "0", "0", "*", "*", "0", "0", self.seq1.as_str(), self.qual1.as_str()].join("\t");
    if !self.id2.is_empty() {
      let entry2:String  = vec![self.id2.as_str(), "141", "*", "0", "0", "*", "*", "0", "0", self.seq2.as_str(), self.qual2.as_str()].join("\t");
      entry = format!("{}\n{}", entry, entry2);
    }

    return entry;
  }
}

/*
#[test]
/// Test to see whether we can convert from fastq to everything else
fn test_fastq_to () {
    let (tx, rx):(std::sync::mpsc::Sender<FastenSeq>,std::sync::mpsc::Receiver<FastenSeq>) = channel();
    read_fastq(tx.clone(), false);

    //assert_eq!(obs_fasta_string, expected_fasta_string, "Convert fastq=>fasta");
    //assert_eq!(obs_sam_string, expected_sam_string, "Convert fastq=>sam");
    //assert_eq!(obs_fastq_string, expected_fastq_string, "Convert fastq=>fastq (self to self)");
}
*/
      
fn main(){
    let mut opts = fasten_base_options();
    opts.optopt("i", "in-format",  "The input format for stdin. FORMAT can be: fastq, fasta, sam.",  "FORMAT");
    opts.optopt("o", "out-format", "The output format for stdin. See --in-format for FORMAT options.", "FORMAT");

    let description:String = format!("Converts between sequence formats.");
    let matches = fasten_base_options_matches(&description, opts);

    let paired_end = matches.opt_present("paired-end");

    let in_format  = matches.opt_default("in-format", "fastq")
                       .unwrap_or(String::from("fastq"))
                       .to_lowercase();
    let out_format = matches.opt_default("out-format","fastq")
                       .unwrap_or(String::from("fastq"))
                       .to_lowercase();

    let (tx, rx):(std::sync::mpsc::Sender<FastenSeq>,std::sync::mpsc::Receiver<FastenSeq>) = channel();

    //let infile = stdin();

    //TODO (?) multithread this 
    match in_format.as_str() {
      "fastq" => {read_fastq(tx, paired_end);}
      "sam"   => {read_sam(tx, paired_end);}
      "fasta" => {read_fasta(tx, paired_end);}
      _ => {panic!("Unknown input format {}", in_format);}
    };

    match out_format.as_str() {
      "fastq" => {write_fastq(rx);}
      "fasta" => {write_fasta(rx);}
      "sam"   => {write_sam(rx);}
      _ => {panic!("Unknown output format {}", out_format);}
    };

}

// I wasn't satisfied with the existing fasta parsers and how they might
// read stdin and so I rolled out my own
/// Read fasta from stdin and transmit it to a channel
fn read_fasta(tx:std::sync::mpsc::Sender<FastenSeq>, paired_end:bool){
    if paired_end {
        logmsg("--paired-end was given but it is ignored in a fasta context");
    }

    // Read the fasta through stdin
    let stdin = stdin();
    //let mut iterator = stdin.lock().lines();

    // Get the first line, ie the first defline, right away
    let mut seq:FastenSeq = FastenSeq::new();
    let bytes = stdin.read_line(&mut seq.id1).unwrap();
    seq.id1 = seq.id1.trim().to_string();
    if bytes == 0 {
        panic!("Zero byte stdin");
    }
    // remove ">"
    let gt_sign = seq.id1.remove(0);
    if gt_sign != '>' {
        panic!("ERROR: first character of first line of stdin is not '>' as expected. Found {}", gt_sign);
    }

    loop{
        let mut buffer = String::new();
        let bytes = stdin.read_line(&mut buffer).unwrap();
        buffer = buffer.trim().to_string();
        // If this is EOF, send the last sequence and break
        if bytes == 0 {
            // Send the last sequence
            // The quality line will be fake and as long as the sequence length
            seq.qual1 = (0..seq.seq1.len()).map(|_| "I").collect::<String>();
            tx.send(seq).expect("Sending seq object to writer");
            break;
        }
        // if we're looking at the next sequence identifier,
        // send off the current sequence and start fresh with
        // the new identifier.
        else if &buffer[0..1]==">" {
            // The quality line will be fake and as long as the sequence length
            seq.qual1 = (0..seq.seq1.len()).map(|_| "I").collect::<String>();
            // Send off the sequence
            tx.send(seq).expect("Sending seq object to writer");

            seq = FastenSeq::new();
            seq.id1 = buffer;
            // remove ">"
            let gt_sign = seq.id1.remove(0);
            if gt_sign != '>' {
                panic!("ERROR: first character of first line of stdin is not '>' as expected. Found {}", gt_sign);
            }
        }
        else {
            seq.seq1 = format!("{}{}", seq.seq1, buffer);
        }
    }

}

/// Read sam from stdin and transmit it to a channel
fn read_sam(tx:std::sync::mpsc::Sender<FastenSeq>, paired_end:bool){
  if paired_end {
    logmsg("--paired-end given but paired-endedness will be determined by sam format flags");
  }

  // TODO check if sorted by name so that the pairs are next to each other

  let mut reader = bam::SamReader::from_path("/dev/stdin").unwrap();
  let mut r      = bam::Record::new();

  loop {
    let mut seq:FastenSeq = FastenSeq::new();

    match reader.read_into(&mut r) {
      Ok(false) => break,
      Ok(true)  => {},
      Err(e)    => panic!("{}", e),
    }
    seq.id1    = String::from(std::str::from_utf8(r.name()).unwrap());
    seq.seq1   = String::from_utf8(r.sequence().to_vec()).unwrap();
    seq.qual1  = String::from_utf8(r.qualities().to_readable()).unwrap();

    // Read from the sam itself whether this is paired end
    if r.flag().is_paired() {
      match reader.read_into(&mut r) {
        Ok(false) => break,
        Ok(true)  => {},
        Err(e)    => panic!("{}", e),
      }
      seq.id2    = String::from(std::str::from_utf8(r.name()).unwrap());
      seq.seq2   = String::from_utf8(r.sequence().to_vec()).unwrap();
      seq.qual2  = String::from_utf8(r.qualities().to_readable()).unwrap();
    }

    tx.send(seq).expect("Sending seq object to writer");
  }
}

/// Read fastq from stdin and transmit it to a channel
fn read_fastq(tx:std::sync::mpsc::Sender<FastenSeq>, paired_end:bool){

  let parser = Parser::new(stdin());

  let mut parser_getter = parser.ref_iter();
  parser_getter.advance().expect("Could not read the first fastq entry");
  while let Some(record1) = parser_getter.get() {
    let mut seq:FastenSeq = FastenSeq::new();
    seq.id1   = std::str::from_utf8(record1.head()).unwrap().to_string();
    seq.seq1  = std::str::from_utf8(record1.seq()).unwrap().to_string();
    seq.qual1 = std::str::from_utf8(record1.qual()).unwrap().to_string();
    if paired_end {
      // get the next entry with advance() and then get()
      match &parser_getter.advance() {
        Ok(_) => {},
        Err(err) => {
          panic!("ERROR: could not read the second entry in a paired end read: {}", err);
        }
      };
      let record2 = &parser_getter.get().expect("ERROR parsing second pair in a paired end read");
      seq.id2   = std::str::from_utf8(record2.head()).unwrap().to_string();
      seq.seq2  = std::str::from_utf8(record2.seq()).unwrap().to_string();
      seq.qual2 = std::str::from_utf8(record2.qual()).unwrap().to_string();
    }

    tx.send(seq).expect("Sending seq object to writer");

    match &parser_getter.advance() {
      Ok(_) => {},
      Err(_) => {break;}
    };
  }
}

/// Read from a channel and print as fastq
fn write_fastq(rx:std::sync::mpsc::Receiver<FastenSeq>){
  let receiver = rx.iter();
  for seq in receiver {
    println!("{}", seq.as_fastq());
  }
}

/// Read from a channel and print as fasta
fn write_fasta(rx:std::sync::mpsc::Receiver<FastenSeq>){
  let receiver = rx.iter();
  for seq in receiver {
    println!("{}", seq.as_fasta());
  }
}

/// Read from a channel and print as sam
fn write_sam(rx:std::sync::mpsc::Receiver<FastenSeq>){
  let receiver = rx.iter();
  for seq in receiver {
    println!("{}", seq.as_sam());
  }
}