// CP/M CMD format, also the TRS-80 Load Module Format (LMF)
// https://en.wikipedia.org/wiki/CMD_file_(CP/M)
// https://www.tim-mann.org/trs80/doc/ldosq1-4.pdf (page 43)
use crate::*;


pub fn format_cmd(segments: &[Segment]) -> Result<Vec<u8>, FormatError> {
    let mut records = Vec::new();
    let mut address;
    for segment in segments {
        address = segment.address;
        for chunk in segment.words.chunks(16) {
            records.push(data_record(chunk, address)?);
            address += 16;
        }
    }
    let start_address = segments.first().map(|s| s.address).unwrap_or(0);
    records.push(terminating_record(start_address)?);

    let mut output = String::new();
    for record in records {
        output.push_str(&record.to_string_plain());
    }
    return Ok(output.into_bytes());
}

fn data_record(words: &[Tracked<Word>], address: usize) -> Result<InhxRecord, FormatError> {
    let Ok(address) = u16::try_from(address) else {
        return Err(FormatError::AddressTooLarge(u16::MAX as usize, address));
    };
    let mut record = InhxRecord::new();
    record.byte(0x01);
    let data_bytes = words.len() as u8;
    record.byte(data_bytes.wrapping_add(2));
    record.le_double(address);
    for word in words {
        if word.value.width > 8 {
            return Err(FormatError::WordTooWide(8, word.width, word.source.clone()));
        }
        record.byte(word.value.value as u8);
    }
    return Ok(record);
}

fn terminating_record(address: usize) -> Result<InhxRecord, FormatError> {
    let Ok(address) = u16::try_from(address) else {
        return Err(FormatError::AddressTooLarge(u16::MAX as usize, address));
    };
    let mut record = InhxRecord::new();
    record.byte(0x02);
    record.byte(0x02);
    record.le_double(address);
    return Ok(record);
}