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use super::Controlfield;
use super::Field;
use super::Record;
use super::Subfield;

const MARC_BREAKER_SF_DELIMITER: &str = "$";
const MARC_BREAKER_SF_DELIMITER_ESCAPE: &str = "{dollar}";

/// Replace bare subfield delimiter values with their escaped version.
pub fn escape_to_breaker(value: &str) -> String {
    value.replace(MARC_BREAKER_SF_DELIMITER, MARC_BREAKER_SF_DELIMITER_ESCAPE)
}

/// Replace escaped subfield delimiter values with the bare version.
pub fn unescape_from_breaker(value: &str) -> String {
    value.replace(MARC_BREAKER_SF_DELIMITER_ESCAPE, MARC_BREAKER_SF_DELIMITER)
}

impl Controlfield {
    pub fn to_breaker(&self) -> String {
        if !self.content().is_empty() {
            format!("={} {}", self.tag(), escape_to_breaker(self.content()))
        } else {
            format!("={}", self.tag())
        }
    }
}

impl Subfield {
    pub fn to_breaker(&self) -> String {
        format!(
            "${}{}",
            escape_to_breaker(self.code()),
            escape_to_breaker(self.content()),
        )
    }
}

impl Field {
    pub fn to_breaker(&self) -> String {
        let mut s = format!(
            "={} {}{}",
            self.tag(),
            if self.ind1() == " " {
                "\\"
            } else {
                self.ind1()
            },
            if self.ind2() == " " {
                "\\"
            } else {
                self.ind2()
            },
        );

        for sf in self.subfields() {
            s += sf.to_breaker().as_str();
        }

        s
    }
}

impl Record {
    /// Creates the MARC Breaker representation of this record as a String.
    pub fn to_breaker(&self) -> String {
        let mut s = format!("=LDR {}", &escape_to_breaker(self.leader()));

        for cfield in self.control_fields() {
            s += format!("\n{}", cfield.to_breaker()).as_str();
        }

        for field in self.fields() {
            s += format!("\n{}", field.to_breaker()).as_str();
        }

        s
    }

    /// Creates a new MARC Record from a MARC Breaker string.
    pub fn from_breaker(breaker: &str) -> Result<Self, String> {
        let mut record = Record::new();

        for line in breaker.lines() {
            record.add_breaker_line(line)?;
        }

        Ok(record)
    }

    /// Process one line of breaker text
    fn add_breaker_line(&mut self, line: &str) -> Result<(), String> {
        let mut len = line.len();
        if len < 4 {
            return Ok(());
        }

        // Step past the opening '=' character
        let line = &line[1..];
        len -= 1;

        let tag = &line[..3];

        if tag.eq("LDR") {
            if len > 4 {
                self.set_leader(&line[4..])?;
            }
            return Ok(());
        }

        // There is a space between the tag and the 1st indicator.

        if tag < "010" {
            let content = if len > 4 {
                unescape_from_breaker(&line[4..])
            } else {
                "".to_string()
            };
            let cf = Controlfield::new(tag, content)?;
            self.control_fields_mut().push(cf);
            return Ok(());
        }

        let mut field = Field::new(tag)?;

        if len > 4 {
            field.set_ind1(line[4..5].replace('\\', " "))?;
        }

        if len > 5 {
            field.set_ind2(line[5..6].replace('\\', " "))?;
        }

        if len > 6 {
            for sf in line[6..].split(MARC_BREAKER_SF_DELIMITER) {
                if sf.is_empty() {
                    continue;
                }
                let subfield = Subfield::new(&sf[..1], if sf.len() > 1 { &sf[1..] } else { "" })?;

                field.subfields_mut().push(subfield);
            }
        }

        self.fields_mut().push(field);

        Ok(())
    }
}