// 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_range32;

pub struct Big5Decoder {

    lead: Option<u8>,

}

impl Big5Decoder {

    pub fn new() -> VariantDecoder {

        VariantDecoder::Big5(Big5Decoder { 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> {

        // If there is a lead but the next byte isn't a valid trail, an

        // error is generated for the lead (+1). Then another iteration checks

        // space, which needs +1 to account for the possibility of astral

        // output or combining pair.

        checked_add(1, self.plus_one_if_lead(byte_length))

    }

    pub fn max_utf8_buffer_length_without_replacement(&self, byte_length: usize) -> Option<usize> {

        // No need to account for REPLACEMENT CHARACTERS.

        // Cases:

        // ASCII: 1 to 1

        // Valid pair: 2 to 2, 2 to 3 or 2 to 4, i.e. worst case 2 to 4

        // lead set and first byte is trail: 1 to 4 worst case

        //

        // When checking for space for the last byte:

        // no lead: the last byte must be ASCII (or fatal error): 1 to 1

        // lead set: space for 4 bytes was already checked when reading the

        // lead, hence the last lead and the last trail together are worst

        // case 2 to 4.

        //

        // If lead set and the input is a single trail byte, the worst-case

        // output is 4, so we need to add one before multiplying if lead is

        // set.

        //

        // Finally, add two so that if input is non-zero, the output is at

        // least 4.

        checked_add(2, checked_mul(2, self.plus_one_if_lead(byte_length)))

    }

    pub fn max_utf8_buffer_length(&self, byte_length: usize) -> Option<usize> {

        // If there is a lead but the next byte isn't a valid trail, an

        // error is generated for the lead (+(1*3)). Then another iteration

        // checks space, which needs +3 to account for the possibility of astral

        // output or combining pair. In between start and end, the worst case

        // is that every byte is bad: *3.

        checked_add(3, checked_mul(3, self.plus_one_if_lead(byte_length)))

    }

    ascii_compatible_two_byte_decoder_functions!(

        {

            // If lead is between 0x81 and 0xFE, inclusive,

            // subtract offset 0x81.

            let non_ascii_minus_offset =

                non_ascii.wrapping_sub(0x81);

            if non_ascii_minus_offset > (0xFE - 0x81) {

                return (DecoderResult::Malformed(1, 0),

                        source.consumed(),

                        handle.written());

            }

            non_ascii_minus_offset

        },

        {

            // If trail is between 0x40 and 0x7E, inclusive,

            // subtract offset 0x40. Else if trail is

            // between 0xA1 and 0xFE, inclusive, subtract

            // offset 0x62.

            // TODO: Find out which range is more probable.

            let mut trail_minus_offset =

                byte.wrapping_sub(0x40);

            if trail_minus_offset > (0x7E - 0x40) {

                let trail_minus_range_start =

                    byte.wrapping_sub(0xA1);

                if trail_minus_range_start >

                   (0xFE - 0xA1) {

                    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 - 0x62;

            }

            let pointer = lead_minus_offset as usize *

                          157usize +

                          trail_minus_offset as usize;

            let rebased_pointer = pointer.wrapping_sub(942);

            let low_bits = big5_low_bits(rebased_pointer);

            if low_bits == 0 {

                match pointer {

                    1133 => {

                        handle.write_big5_combination(0x00CAu16,

                                                      0x0304u16)

                    }

                    1135 => {

                        handle.write_big5_combination(0x00CAu16,

                                                      0x030Cu16)

                    }

                    1164 => {

                        handle.write_big5_combination(0x00EAu16,

                                                      0x0304u16)

                    }

                    1166 => {

                        handle.write_big5_combination(0x00EAu16,

                                                      0x030Cu16)

                    }

                    _ => {

                        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());

                    }

                }

            } else if big5_is_astral(rebased_pointer) {

                handle.write_astral(u32::from(low_bits) |

                                    0x20000u32)

            } else {

                handle.write_bmp_excl_ascii(low_bits)

            }

        },

        self,

        non_ascii,

        byte,

        lead_minus_offset,

        unread_handle_trail,

        source,

        handle,

        'outermost,

        copy_ascii_from_check_space_astral,

        check_space_astral,

        false);

}

pub struct Big5Encoder;

impl Big5Encoder {

    pub fn new(encoding: &'static Encoding) -> Encoder {

        Encoder::new(encoding, VariantEncoder::Big5(Big5Encoder))

    }

    pub fn max_buffer_length_from_utf16_without_replacement(

        &self,

        u16_length: usize,

    ) -> Option<usize> {

        // Astral: 2 to 2

        // ASCII: 1 to 1

        // Other: 1 to 2

        u16_length.checked_mul(2)

    }

    pub fn max_buffer_length_from_utf8_without_replacement(

        &self,

        byte_length: usize,

    ) -> Option<usize> {

        // Astral: 4 to 2

        // Upper BMP: 3 to 2

        // Lower BMP: 2 to 2

        // ASCII: 1 to 1

        byte_length.checked_add(1)

    }

    ascii_compatible_encoder_functions!(

        {

            // For simplicity, unified ideographs

            // in the pointer range 11206...11212 are handled

            // as Level 1 Hanzi.

            if let Some((lead, trail)) = big5_level1_hanzi_encode(bmp) {

                handle.write_two(lead, trail)

            } else {

                let pointer = if let Some(pointer) = big5_box_encode(bmp) {

                    pointer

                } else if let Some(pointer) = big5_other_encode(bmp) {

                    pointer

                } else {

                    return (

                        EncoderResult::unmappable_from_bmp(bmp),

                        source.consumed(),

                        handle.written(),

                    );

                };

                let lead = pointer / 157 + 0x81;

                let remainder = pointer % 157;

                let trail = if remainder < 0x3F {

                    remainder + 0x40

                } else {

                    remainder + 0x62

                };

                handle.write_two(lead as u8, trail as u8)

            }

        },

        {

            if in_inclusive_range32(astral as u32, 0x2008A, 0x2F8A6) {

                if let Some(rebased_pointer) = big5_astral_encode(astral as u16) {

                    // big5_astral_encode returns rebased pointer,

                    // so adding 0x87 instead of 0x81.

                    let lead = rebased_pointer / 157 + 0x87;

                    let remainder = rebased_pointer % 157;

                    let trail = if remainder < 0x3F {

                        remainder + 0x40

                    } else {

                        remainder + 0x62

                    };

                    handle.write_two(lead as u8, trail as u8)

                } else {

                    return (

                        EncoderResult::Unmappable(astral),

                        source.consumed(),

                        handle.written(),

                    );

                }

            } else {

                return (

                    EncoderResult::Unmappable(astral),

                    source.consumed(),

                    handle.written(),

                );

            }

        },

        bmp,

        astral,

        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(all(test, feature = "alloc"))]

mod tests {

    use super::super::testing::*;

    use super::super::*;

    fn decode_big5(bytes: &[u8], expect: &str) {

        decode(BIG5, bytes, expect);

    }

    fn encode_big5(string: &str, expect: &[u8]) {

        encode(BIG5, string, expect);

    }

    #[test]

    fn test_big5_decode() {

        // Empty

        decode_big5(b"", &"");

        // ASCII

        decode_big5(&[0x61u8, 0x62u8], &"\u{0061}\u{0062}");

        // Edge cases

        decode_big5(&[0x87u8, 0x40u8], &"\u{43F0}");

        decode_big5(&[0xFEu8, 0xFEu8], &"\u{79D4}");

        decode_big5(&[0xFEu8, 0xFDu8], &"\u{2910D}");

        decode_big5(&[0x88u8, 0x62u8], &"\u{00CA}\u{0304}");

        decode_big5(&[0x88u8, 0x64u8], &"\u{00CA}\u{030C}");

        decode_big5(&[0x88u8, 0x66u8], &"\u{00CA}");

        decode_big5(&[0x88u8, 0xA3u8], &"\u{00EA}\u{0304}");

        decode_big5(&[0x88u8, 0xA5u8], &"\u{00EA}\u{030C}");

        decode_big5(&[0x88u8, 0xA7u8], &"\u{00EA}");

        decode_big5(&[0x99u8, 0xD4u8], &"\u{8991}");

        decode_big5(&[0x99u8, 0xD5u8], &"\u{27967}");

        decode_big5(&[0x99u8, 0xD6u8], &"\u{8A29}");

        // Edge cases surrounded with ASCII

        decode_big5(

            &[0x61u8, 0x87u8, 0x40u8, 0x62u8],

            &"\u{0061}\u{43F0}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0xFEu8, 0xFEu8, 0x62u8],

            &"\u{0061}\u{79D4}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0xFEu8, 0xFDu8, 0x62u8],

            &"\u{0061}\u{2910D}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0x62u8, 0x62u8],

            &"\u{0061}\u{00CA}\u{0304}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0x64u8, 0x62u8],

            &"\u{0061}\u{00CA}\u{030C}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0x66u8, 0x62u8],

            &"\u{0061}\u{00CA}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0xA3u8, 0x62u8],

            &"\u{0061}\u{00EA}\u{0304}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0xA5u8, 0x62u8],

            &"\u{0061}\u{00EA}\u{030C}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x88u8, 0xA7u8, 0x62u8],

            &"\u{0061}\u{00EA}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x99u8, 0xD4u8, 0x62u8],

            &"\u{0061}\u{8991}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x99u8, 0xD5u8, 0x62u8],

            &"\u{0061}\u{27967}\u{0062}",

        );

        decode_big5(

            &[0x61u8, 0x99u8, 0xD6u8, 0x62u8],

            &"\u{0061}\u{8A29}\u{0062}",

        );

        // Bad sequences

        decode_big5(&[0x80u8, 0x61u8], &"\u{FFFD}\u{0061}");

        decode_big5(&[0xFFu8, 0x61u8], &"\u{FFFD}\u{0061}");

        decode_big5(&[0xFEu8, 0x39u8], &"\u{FFFD}\u{0039}");

        decode_big5(&[0x87u8, 0x66u8], &"\u{FFFD}\u{0066}");

        decode_big5(&[0x81u8, 0x40u8], &"\u{FFFD}\u{0040}");

        decode_big5(&[0x61u8, 0x81u8], &"\u{0061}\u{FFFD}");

    }

    #[test]

    fn test_big5_encode() {

        // Empty

        encode_big5("", b"");

        // ASCII

        encode_big5("\u{0061}\u{0062}", b"\x61\x62");

        if !cfg!(miri) {

            // Miri is too slow

            // Edge cases

            encode_big5("\u{9EA6}\u{0061}", b"麦\x61");

            encode_big5("\u{2626B}\u{0061}", b"𦉫\x61");

            encode_big5("\u{3000}", b"\xA1\x40");

            encode_big5("\u{20AC}", b"\xA3\xE1");

            encode_big5("\u{4E00}", b"\xA4\x40");

            encode_big5("\u{27607}", b"\xC8\xA4");

            encode_big5("\u{FFE2}", b"\xC8\xCD");

            encode_big5("\u{79D4}", b"\xFE\xFE");

            // Not in index

            encode_big5("\u{2603}\u{0061}", b"☃\x61");

        }

        // duplicate low bits

        encode_big5("\u{203B5}", b"\xFD\x6A");

        encode_big5("\u{25605}", b"\xFE\x46");

        // prefer last

        encode_big5("\u{2550}", b"\xF9\xF9");

    }

    #[test]

    #[cfg_attr(miri, ignore)] // Miri is too slow

    fn test_big5_decode_all() {

        let input = include_bytes!("test_data/big5_in.txt");

        let expectation = include_str!("test_data/big5_in_ref.txt");

        let (cow, had_errors) = BIG5.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_big5_encode_all() {

        let input = include_str!("test_data/big5_out.txt");

        let expectation = include_bytes!("test_data/big5_out_ref.txt");

        let (cow, encoding, had_errors) = BIG5.encode(input);

        assert!(!had_errors, "Should not have had errors.");

        assert_eq!(encoding, BIG5);

        assert_eq!(&cow[..], &expectation[..]);

    }

    #[test]

    #[cfg_attr(miri, ignore)] // Miri is too slow

    fn test_big5_encode_from_two_low_surrogates() {

        let expectation = b"��";

        let mut output = [0u8; 40];

        let mut encoder = BIG5.new_encoder();

        let (result, read, written, had_errors) =

            encoder.encode_from_utf16(&[0xDC00u16, 0xDEDEu16], &mut output[..], true);

        assert_eq!(result, CoderResult::InputEmpty);

        assert_eq!(read, 2);

        assert_eq!(written, expectation.len());

        assert!(had_errors);

        assert_eq!(&output[..written], expectation);

    }

}