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    // Copyright Mozilla Foundation. See the COPYRIGHT
    // file at the top-level directory of this distribution.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    use super::*;
    use crate::data::*;
    use crate::handles::*;
    use crate::variant::*;
    // Rust 1.14.0 requires the following despite the asterisk above.
    use super::in_inclusive_range;
    use super::in_inclusive_range16;

    pub struct ShiftJisDecoder {
        lead: Option<u8>,
    }

    impl ShiftJisDecoder {
        pub fn new() -> VariantDecoder {
            VariantDecoder::ShiftJis(ShiftJisDecoder { lead: None })
        }

        pub fn in_neutral_state(&self) -> bool {
            self.lead.is_none()
        }

        fn plus_one_if_lead(&self, byte_length: usize) -> Option<usize> {
            byte_length.checked_add(match self.lead {
                None => 0,
                Some(_) => 1,
            })
        }

        pub fn max_utf16_buffer_length(&self, byte_length: usize) -> Option<usize> {
            self.plus_one_if_lead(byte_length)
        }

        pub fn max_utf8_buffer_length_without_replacement(&self, byte_length: usize) -> Option<usize> {
            // worst case: 1 to 3 (half-width katakana)
            self.max_utf8_buffer_length(byte_length)
        }

        pub fn max_utf8_buffer_length(&self, byte_length: usize) -> Option<usize> {
            checked_mul(3, self.plus_one_if_lead(byte_length))
        }

        ascii_compatible_two_byte_decoder_functions!(
            {
               // If lead is between 0x81 and 0x9F, inclusive,
               // subtract offset 0x81. Else if lead is
               // between 0xE0 and 0xFC, inclusive, subtract
               // offset 0xC1. Else if lead is between
               // 0xA1 and 0xDF, inclusive, map to half-width
               // Katakana. Else if lead is 0x80, pass through.
                let mut non_ascii_minus_offset =
                    non_ascii.wrapping_sub(0x81);
                if non_ascii_minus_offset > (0x9F - 0x81) {
                    let non_ascii_minus_range_start = non_ascii.wrapping_sub(0xE0);
                    if non_ascii_minus_range_start > (0xFC - 0xE0) {
                        let non_ascii_minus_half_with_katakana_start = non_ascii.wrapping_sub(0xA1);
                        if non_ascii_minus_half_with_katakana_start > (0xDF - 0xA1) {
                            if non_ascii == 0x80 {
                                handle.write_mid_bmp(0x80);
                                // Not caring about optimizing subsequent non-ASCII
                                continue 'outermost;
                            }
                            return (DecoderResult::Malformed(1, 0),
                                    source.consumed(),
                                    handle.written());
                        }
                        handle.write_upper_bmp(0xFF61 + u16::from(non_ascii_minus_half_with_katakana_start));
                        // Not caring about optimizing subsequent non-ASCII
                        continue 'outermost;
                    }
                    non_ascii_minus_offset = non_ascii - 0xC1;
                }
                non_ascii_minus_offset
            },
            {
                // If trail is between 0x40 and 0x7E, inclusive,
                // subtract offset 0x40. Else if trail is
                // between 0x80 and 0xFC, inclusive, subtract
                // offset 0x41.
                // Fast-track Hiragana (60% according to Lunde)
                // and Katakana (10% acconding to Lunde).
                // Hiragana doesn't cross 0x7F, but Katakana does.
                // We can check for Hiragana before normalizing
                // trail.
                let trail_minus_hiragana = byte.wrapping_sub(0x9F);
                if lead_minus_offset == 0x01 && trail_minus_hiragana < 0x53 {
                // Hiragana
                    handle.write_upper_bmp(0x3041 + u16::from(trail_minus_hiragana))
                } else {
                    let mut trail_minus_offset =
                        byte.wrapping_sub(0x40);
                    if trail_minus_offset > (0x7E - 0x40) {
                        let trail_minus_range_start =
                            byte.wrapping_sub(0x80);
                        if trail_minus_range_start > (0xFC - 0x80) {
                            if byte < 0x80 {
                                return (DecoderResult::Malformed(1, 0),
                                        unread_handle_trail.unread(),
                                        handle.written());
                            }
                            return (DecoderResult::Malformed(2, 0),
                                    unread_handle_trail.consumed(),
                                    handle.written());
                        }
                        trail_minus_offset = byte - 0x41;
                    }
                    if lead_minus_offset == 0x02 &&
                       trail_minus_offset < 0x56 {
                        // Katakana
                        handle.write_upper_bmp(0x30A1 + u16::from(trail_minus_offset))
                    } else {
                        let pointer = lead_minus_offset as usize *
                                      188usize +
                                      trail_minus_offset as usize;
                        let level1_pointer = pointer.wrapping_sub(1410);
                        if level1_pointer < JIS0208_LEVEL1_KANJI.len() {
                            handle.write_upper_bmp(JIS0208_LEVEL1_KANJI[level1_pointer])
                        } else {
                            let level2_pointer = pointer.wrapping_sub(4418);
                            if level2_pointer <
                               JIS0208_LEVEL2_AND_ADDITIONAL_KANJI.len() {
                                handle.write_upper_bmp(JIS0208_LEVEL2_AND_ADDITIONAL_KANJI[level2_pointer])
                            } else {
                                let upper_ibm_pointer = pointer.wrapping_sub(10744);
                                if upper_ibm_pointer < IBM_KANJI.len() {
                                    handle.write_upper_bmp(IBM_KANJI[upper_ibm_pointer])
                                } else {
                                    let lower_ibm_pointer = pointer.wrapping_sub(8272);
                                    if lower_ibm_pointer < IBM_KANJI.len() {
                                        handle.write_upper_bmp(IBM_KANJI[lower_ibm_pointer])
                                    } else if in_inclusive_range(pointer, 8836, 10715) {
                                        handle.write_upper_bmp((0xE000 - 8836 + pointer) as u16)
                                    } else if let Some(bmp) = jis0208_symbol_decode(pointer) {
                                        handle.write_bmp_excl_ascii(bmp)
                                    } else if let Some(bmp) = jis0208_range_decode(pointer) {
                                        handle.write_bmp_excl_ascii(bmp)
                                    } else {
                                        if byte < 0x80 {
                                            return (DecoderResult::Malformed(1, 0),
                                                    unread_handle_trail.unread(),
                                                    handle.written());
                                        }
                                        return (DecoderResult::Malformed(2, 0),
                                                unread_handle_trail.consumed(),
                                                handle.written());
                                    }
                                }
                            }
                        }
                    }
                }
            },
            self,
            non_ascii,
            byte,
            lead_minus_offset,
            unread_handle_trail,
            source,
            handle,
            'outermost,
            copy_ascii_from_check_space_bmp,
            check_space_bmp,
            false);
    }

    #[cfg(feature = "fast-kanji-encode")]
    #[inline(always)]
    fn encode_kanji(bmp: u16) -> Option<(u8, u8)> {
        jis0208_kanji_shift_jis_encode(bmp)
    }

    #[cfg(not(feature = "fast-kanji-encode"))]
    #[inline(always)]
    fn encode_kanji(bmp: u16) -> Option<(u8, u8)> {
        if let Some((lead, trail)) = jis0208_level1_kanji_shift_jis_encode(bmp) {
            return Some((lead, trail));
        }
        let pointer = if 0x4EDD == bmp {
            // Ideograph on the symbol row!
            23
        } else if let Some(pos) = jis0208_level2_and_additional_kanji_encode(bmp) {
            4418 + pos
        } else if let Some(pos) = position(&IBM_KANJI[..], bmp) {
            10744 + pos
        } else {
            return None;
        };
        let lead = pointer / 188;
        let lead_offset = if lead < 0x1F { 0x81usize } else { 0xC1usize };
        let trail = pointer % 188;
        let trail_offset = if trail < 0x3F { 0x40usize } else { 0x41usize };
        Some(((lead + lead_offset) as u8, (trail + trail_offset) as u8))
    }

    pub struct ShiftJisEncoder;

    impl ShiftJisEncoder {
        pub fn new(encoding: &'static Encoding) -> Encoder {
            Encoder::new(encoding, VariantEncoder::ShiftJis(ShiftJisEncoder))
        }

        pub fn max_buffer_length_from_utf16_without_replacement(
            &self,
            u16_length: usize,
        ) -> Option<usize> {
            u16_length.checked_mul(2)
        }

        pub fn max_buffer_length_from_utf8_without_replacement(
            &self,
            byte_length: usize,
        ) -> Option<usize> {
            byte_length.checked_add(1)
        }

        ascii_compatible_bmp_encoder_functions!(
            {
                // Lunde says 60% Hiragana, 30% Kanji, 10% Katakana
                let bmp_minus_hiragana = bmp.wrapping_sub(0x3041);
                if bmp_minus_hiragana < 0x53 {
                    handle.write_two(0x82, 0x9F + bmp_minus_hiragana as u8)
                } else if in_inclusive_range16(bmp, 0x4E00, 0x9FA0) {
                    if let Some((lead, trail)) = encode_kanji(bmp) {
                        handle.write_two(lead, trail)
                    } else {
                        return (
                            EncoderResult::unmappable_from_bmp(bmp),
                            source.consumed(),
                            handle.written(),
                        );
                    }
                } else {
                    let bmp_minus_katakana = bmp.wrapping_sub(0x30A1);
                    if bmp_minus_katakana < 0x56 {
                        let trail_offset = if bmp_minus_katakana < 0x3F {
                            0x40
                        } else {
                            0x41
                        };
                        handle.write_two(0x83, (trail_offset + bmp_minus_katakana) as u8)
                    } else {
                        let bmp_minus_space = bmp.wrapping_sub(0x3000);
                        if bmp_minus_space < 3 {
                            // fast-track common punctuation
                            handle.write_two(0x81, 0x40 + bmp_minus_space as u8)
                        } else if bmp == 0xA5 {
                            handle.write_one(0x5Cu8)
                        } else if bmp == 0x80 {
                            handle.write_one(0x80u8)
                        } else if bmp == 0x203E {
                            handle.write_one(0x7Eu8)
                        } else if in_inclusive_range16(bmp, 0xFF61, 0xFF9F) {
                            handle.write_one((bmp - (0xFF61 - 0xA1)) as u8)
                        } else if bmp == 0x2212 {
                            handle.write_two(0x81u8, 0x7Cu8)
                        } else {
                            let bmp_minus_roman = bmp.wrapping_sub(0x2170);
                            let pointer = if bmp_minus_roman <= (0x2179 - 0x2170) {
                                10716 + bmp_minus_roman as usize
                            } else if let Some(pointer) = jis0208_range_encode(bmp) {
                                pointer
                            } else if in_inclusive_range16(bmp, 0xFA0E, 0xFA2D)
                                || bmp == 0xF929
                                || bmp == 0xF9DC
                            {
                                // Guaranteed to be found in IBM_KANJI
                                let pos = position(&IBM_KANJI[..], bmp).unwrap();
                                10744 + pos
                            } else if let Some(pointer) = jis0208_symbol_encode(bmp) {
                                pointer
                            } else {
                                return (
                                    EncoderResult::unmappable_from_bmp(bmp),
                                    source.consumed(),
                                    handle.written(),
                                );
                            };
                            let lead = pointer / 188;
                            let lead_offset = if lead < 0x1F { 0x81usize } else { 0xC1usize };
                            let trail = pointer % 188;
                            let trail_offset = if trail < 0x3F { 0x40usize } else { 0x41usize };
                            handle.write_two((lead + lead_offset) as u8, (trail + trail_offset) as u8)
                        }
                    }
                }
            },
            bmp,
            self,
            source,
            handle,
            copy_ascii_to_check_space_two,
            check_space_two,
            false
        );
    }

    // Any copyright to the test code below this comment is dedicated to the
    // Public Domain. http://creativecommons.org/publicdomain/zero/1.0/

    #[cfg(test)]
    mod tests {
        use super::super::testing::*;
        use super::super::*;

        fn decode_shift_jis(bytes: &[u8], expect: &str) {
            decode(SHIFT_JIS, bytes, expect);
        }

        fn encode_shift_jis(string: &str, expect: &[u8]) {
            encode(SHIFT_JIS, string, expect);
        }

        #[test]
        fn test_shift_jis_decode() {
            // Empty
            decode_shift_jis(b"", &"");

            // ASCII
            decode_shift_jis(b"\x61\x62", "\u{0061}\u{0062}");

            // Half-width
            decode_shift_jis(b"\xA1", "\u{FF61}");
            decode_shift_jis(b"\xDF", "\u{FF9F}");
            decode_shift_jis(b"\xA0", "\u{FFFD}");
            decode_shift_jis(b"\xE0", "\u{FFFD}");
            decode_shift_jis(b"\xA0+", "\u{FFFD}+");
            decode_shift_jis(b"\xE0+", "\u{FFFD}+");

            // EUDC
            decode_shift_jis(b"\xF0\x40", "\u{E000}");
            decode_shift_jis(b"\xF9\xFC", "\u{E757}");
            decode_shift_jis(b"\xEF\xFC", "\u{FFFD}");
            decode_shift_jis(b"\xFA\x40", "\u{2170}");

            // JIS 0208
            decode_shift_jis(b"\x81\x40", "\u{3000}");
            decode_shift_jis(b"\x81\x3F", "\u{FFFD}?");
            decode_shift_jis(b"\xEE\xFC", "\u{FF02}");
            decode_shift_jis(b"\xEE\xFD", "\u{FFFD}");
            decode_shift_jis(b"\xFA\x40", "\u{2170}");
            decode_shift_jis(b"\xFA\x3F", "\u{FFFD}?");
            decode_shift_jis(b"\xFC\x4B", "\u{9ED1}");
            decode_shift_jis(b"\xFC\x4C", "\u{FFFD}L");
            //
        }

        #[test]
        fn test_shift_jis_encode() {
            // Empty
            encode_shift_jis("", b"");

            // ASCII
            encode_shift_jis("\u{0061}\u{0062}", b"\x61\x62");

            // Exceptional code points
            encode_shift_jis("\u{0080}", b"\x80");
            encode_shift_jis("\u{00A5}", b"\x5C");
            encode_shift_jis("\u{203E}", b"\x7E");
            encode_shift_jis("\u{2212}", b"\x81\x7C");

            // Half-width
            encode_shift_jis("\u{FF61}", b"\xA1");
            encode_shift_jis("\u{FF9F}", b"\xDF");

            // EUDC
            encode_shift_jis("\u{E000}", b"&#57344;");
            encode_shift_jis("\u{E757}", b"&#59223;");

            // JIS 0212
            encode_shift_jis("\u{02D8}", b"&#728;");

            // JIS 0208
            encode_shift_jis("\u{3000}", b"\x81\x40");
            encode_shift_jis("\u{FF02}", b"\xFA\x57");
            encode_shift_jis("\u{2170}", b"\xFA\x40");
            encode_shift_jis("\u{9ED1}", b"\xFC\x4B");
        }

        #[test]
        #[cfg_attr(miri, ignore)] // Miri is too slow
        fn test_shift_jis_decode_all() {
            let input = include_bytes!("test_data/shift_jis_in.txt");
            let expectation = include_str!("test_data/shift_jis_in_ref.txt");
            let (cow, had_errors) = SHIFT_JIS.decode_without_bom_handling(input);
            assert!(had_errors, "Should have had errors.");
            assert_eq!(&cow[..], expectation);
        }

        #[test]
        #[cfg_attr(miri, ignore)] // Miri is too slow
        fn test_shift_jis_encode_all() {
            let input = include_str!("test_data/shift_jis_out.txt");
            let expectation = include_bytes!("test_data/shift_jis_out_ref.txt");
            let (cow, encoding, had_errors) = SHIFT_JIS.encode(input);
            assert!(!had_errors, "Should not have had errors.");
            assert_eq!(encoding, SHIFT_JIS);
            assert_eq!(&cow[..], &expectation[..]);
        }

        #[test]
        fn test_shift_jis_half_width_katakana_length() {
            let mut output = [0u8; 20];
            let mut decoder = SHIFT_JIS.new_decoder();
            {
                let needed = decoder
                    .max_utf8_buffer_length_without_replacement(1)
                    .unwrap();
                let (result, read, written) =
                    decoder.decode_to_utf8_without_replacement(b"\xA1", &mut output[..needed], true);
                assert_eq!(result, DecoderResult::InputEmpty);
                assert_eq!(read, 1);
                assert_eq!(written, 3);
                assert_eq!(output[0], 0xEF);
                assert_eq!(output[1], 0xBD);
                assert_eq!(output[2], 0xA1);
            }
        }
    }