//! Serialised Global Trade Item Number
//!
//! This is a combination of a GTIN and a serial number which allows an item to be uniquely
//! identified.
use crate::epc::{EPCValue, EPC};
use crate::error::{ParseError, Result};
use crate::util::{extract_indicator, read_string, uri_encode, zero_pad};
use crate::{ApplicationIdentifier, GS1, GTIN};
use bitreader::BitReader;

/// 96-bit Serialised Global Trade Item Number
///
/// This comprises a GTIN, a filter value (which is used by RFID readers), and a numeric serial
/// number.
#[derive(PartialEq, Debug)]
pub struct SGTIN96 {
    /// Filter value to allow RFID readers to select the type of tag to read.
    pub filter: u8,
    /// Global Trade Item Number
    pub gtin: GTIN,
    /// Item serial number
    pub serial: u64,
}

impl EPC for SGTIN96 {
    // GS1 EPC TDS section 6.3.1
    fn to_uri(&self) -> String {
        format!(
            "urn:epc:id:sgtin:{}.{}{}.{}",
            zero_pad(self.gtin.company.to_string(), self.gtin.company_digits),
            self.gtin.indicator,
            zero_pad(self.gtin.item.to_string(), 12 - self.gtin.company_digits),
            self.serial
        )
    }

    fn to_tag_uri(&self) -> String {
        format!(
            "urn:epc:tag:sgtin-96:{}.{}.{}{}.{}",
            self.filter,
            zero_pad(self.gtin.company.to_string(), self.gtin.company_digits),
            self.gtin.indicator,
            zero_pad(self.gtin.item.to_string(), 12 - self.gtin.company_digits),
            self.serial
        )
    }

    fn get_value(&self) -> EPCValue {
        EPCValue::SGTIN96(self)
    }
}

impl GS1 for SGTIN96 {
    fn to_gs1(&self) -> String {
        let gtin_gs1 = self.gtin.to_gs1();
        format!(
            "{} ({:0>2}) {}",
            gtin_gs1,
            ApplicationIdentifier::SerialNumber as u16,
            self.serial
        )
    }
}

/// 198-bit Serialised Global Trade Item Number
///
/// This comprises a GTIN, a filter value (which is used by RFID readers), and an
/// alphanumeric serial number which is encoded using 7-bit ASCII.
#[derive(PartialEq, Debug)]
pub struct SGTIN198 {
    /// Filter value to allow RFID readers to select tags to read
    pub filter: u8,
    /// Global Trade Item Number
    pub gtin: GTIN,
    /// Alphanumeric serial number
    pub serial: String,
}

impl EPC for SGTIN198 {
    // GS1 EPC TDS section 6.3.1
    fn to_uri(&self) -> String {
        format!(
            "urn:epc:id:sgtin:{}.{}{}.{}",
            zero_pad(self.gtin.company.to_string(), self.gtin.company_digits),
            self.gtin.indicator,
            zero_pad(self.gtin.item.to_string(), 12 - self.gtin.company_digits),
            uri_encode(self.serial.to_string())
        )
    }

    fn to_tag_uri(&self) -> String {
        format!(
            "urn:epc:tag:sgtin-198:{}.{}.{}{}.{}",
            self.filter,
            zero_pad(self.gtin.company.to_string(), self.gtin.company_digits),
            self.gtin.indicator,
            zero_pad(self.gtin.item.to_string(), 12 - self.gtin.company_digits),
            uri_encode(self.serial.to_string())
        )
    }

    fn get_value(&self) -> EPCValue {
        EPCValue::SGTIN198(self)
    }
}

impl GS1 for SGTIN198 {
    fn to_gs1(&self) -> String {
        let gtin_gs1 = self.gtin.to_gs1();
        format!(
            "{} ({:0>2}) {}",
            gtin_gs1,
            ApplicationIdentifier::SerialNumber as u16,
            self.serial
        )
    }
}

// Calculate the number of digits in the decimal representation of a SGTIN
// company code from the partition ID.
// GS1 EPC TDS Table 14-2
fn company_digits(partition: u8) -> usize {
    12 - partition as usize
}

fn item_digits(partition: u8) -> usize {
    13 - company_digits(partition)
}

// GS1 EPC TDS Table 14-2
fn partition_bits(partition: u8) -> Result<(u8, u8)> {
    Ok(match partition {
        0 => (40, 4),
        1 => (37, 7),
        2 => (34, 10),
        3 => (30, 14),
        4 => (27, 17),
        5 => (24, 20),
        6 => (20, 24),
        _ => {
            return Err(Box::new(ParseError()));
        }
    })
}

// GS1 EPC TDC Section 14.5.1
pub(super) fn decode_sgtin96(data: &[u8]) -> Result<Box<dyn EPC>> {
    let mut reader = BitReader::new(data);

    let filter = reader.read_u8(3)?;
    let partition = reader.read_u8(3)?;
    let (company_bits, item_bits) = partition_bits(partition)?;
    let company = reader.read_u64(company_bits)?;
    let item = reader.read_u64(item_bits)?;
    let (item, indicator) = extract_indicator(item, item_digits(partition))?;
    let serial = reader.read_u64(38)?;

    Ok(Box::new(SGTIN96 {
        filter,
        gtin: GTIN {
            company,
            company_digits: company_digits(partition),
            item,
            indicator,
        },
        serial,
    }))
}

// GS1 EPC TDC Section 14.5.1.2
pub(super) fn decode_sgtin198(data: &[u8]) -> Result<Box<dyn EPC>> {
    let mut reader = BitReader::new(data);

    let filter = reader.read_u8(3)?;
    let partition = reader.read_u8(3)?;
    let (company_bits, item_bits) = partition_bits(partition)?;
    let company = reader.read_u64(company_bits)?;
    let item = reader.read_u64(item_bits)?;
    let (item, indicator) = extract_indicator(item, item_digits(partition))?;
    let serial = read_string(reader, 140)?;

    Ok(Box::new(SGTIN198 {
        filter,
        gtin: GTIN {
            company,
            company_digits: company_digits(partition),
            item,
            indicator,
        },
        serial,
    }))
}