// Copyright 2019 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//! Functionality for serializing CBOR values into bytes.

use super::values::{Constants, Value, ValueImpl};

use alloc::vec::Vec;

/// Possible errors from a serialization operation.

#[derive(Debug, PartialEq)]

pub enum EncoderError {

    TooMuchNesting,

    DuplicateMapKey,

}

/// Convert a [`Value`] to serialized CBOR data, consuming it along the way and appending to the provided vector.

/// Maximum level of nesting supported is 127; more deeply nested structures will fail with

/// [`EncoderError::TooMuchNesting`].

pub fn write(value: Value, encoded_cbor: &mut Vec<u8>) -> Result<(), EncoderError> {

    write_nested(value, encoded_cbor, Some(i8::MAX))

}

/// Convert a [`Value`] to serialized CBOR data, consuming it along the way and appending to the provided vector.  If

/// `max_nest` is `Some(max)`, then nested structures are only supported up to the given limit (returning

/// [`DecoderError::TooMuchNesting`] if the limit is hit).

pub fn write_nested(

    value: Value,

    encoded_cbor: &mut Vec<u8>,

    max_nest: Option<i8>,

) -> Result<(), EncoderError> {

    let mut writer = Writer::new(encoded_cbor);

    writer.encode_cbor(value, max_nest)

}

struct Writer<'a> {

    encoded_cbor: &'a mut Vec<u8>,

}

impl<'a> Writer<'a> {

    pub fn new(encoded_cbor: &mut Vec<u8>) -> Writer<'_> {

        Writer { encoded_cbor }

    }

    fn encode_cbor(

        &mut self,

        value: Value,

        remaining_depth: Option<i8>,

    ) -> Result<(), EncoderError> {

        if remaining_depth.is_some_and(|d| d < 0) {

            return Err(EncoderError::TooMuchNesting);

        }

        let type_label = value.0.type_label();

        match value.0 {

            ValueImpl::Unsigned(unsigned) => self.start_item(type_label, unsigned),

            ValueImpl::Negative(negative) => self.start_item(type_label, -(negative + 1) as u64),

            ValueImpl::ByteString(byte_string) => {

                self.start_item(type_label, byte_string.len() as u64);

                self.encoded_cbor.extend(byte_string);

            }

            ValueImpl::TextString(text_string) => {

                self.start_item(type_label, text_string.len() as u64);

                self.encoded_cbor.extend(text_string.into_bytes());

            }

            ValueImpl::Array(array) => {

                self.start_item(type_label, array.len() as u64);

                for el in array {

                    self.encode_cbor(el, remaining_depth.map(|d| d - 1))?;

                }

            }

            ValueImpl::Map(map) => {

                self.start_item(type_label, map.len() as u64);

                for (k, v) in map {

                    self.encode_cbor(k, remaining_depth.map(|d| d - 1))?;

                    self.encode_cbor(v, remaining_depth.map(|d| d - 1))?;

                }

            }

            ValueImpl::Tag(tag, inner_value) => {

                self.start_item(type_label, tag);

                self.encode_cbor(*inner_value, remaining_depth.map(|d| d - 1))?;

            }

            ValueImpl::Simple(simple_value) => self.start_item(type_label, simple_value as u64),

        }

        Ok(())

    }

    fn start_item(&mut self, type_label: u8, size: u64) {

        let (mut first_byte, shift) = match size {

            0..=23 => (size as u8, 0),

            24..=0xFF => (Constants::ADDITIONAL_INFORMATION_1_BYTE, 1),

            0x100..=0xFFFF => (Constants::ADDITIONAL_INFORMATION_2_BYTES, 2),

            0x10000..=0xFFFF_FFFF => (Constants::ADDITIONAL_INFORMATION_4_BYTES, 4),

            _ => (Constants::ADDITIONAL_INFORMATION_8_BYTES, 8),

        };

        first_byte |= type_label << Constants::MAJOR_TYPE_BIT_SHIFT;

        self.encoded_cbor.push(first_byte);

        for i in (0..shift).rev() {

            self.encoded_cbor.push((size >> (i * 8)) as u8);

        }

    }

}

#[cfg(test)]

mod test {

    use super::*;

    use crate::{

        cbor_array, cbor_array_vec, cbor_bytes, cbor_false, cbor_int, cbor_map, cbor_null,

        cbor_tagged, cbor_text, cbor_true, cbor_undefined,

    };

    use alloc::vec;

    fn write_return(value: Value) -> Option<Vec<u8>> {

        let mut encoded_cbor = Vec::new();

        if write(value, &mut encoded_cbor).is_ok() {

            Some(encoded_cbor)

        } else {

            None

        }

    }

    #[test]

    fn test_write_unsigned() {

        let cases = vec![

            (0, vec![0x00]),

            (1, vec![0x01]),

            (10, vec![0x0A]),

            (23, vec![0x17]),

            (24, vec![0x18, 0x18]),

            (25, vec![0x18, 0x19]),

            (100, vec![0x18, 0x64]),

            (1000, vec![0x19, 0x03, 0xE8]),

            (1000000, vec![0x1A, 0x00, 0x0F, 0x42, 0x40]),

            (0xFFFFFFFF, vec![0x1A, 0xFF, 0xFF, 0xFF, 0xFF]),

            (

                0x100000000,

                vec![0x1B, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00],

            ),

            (

                i64::MAX,

                vec![0x1B, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF],

            ),

        ];

        for (unsigned, correct_cbor) in cases {

            assert_eq!(write_return(cbor_int!(unsigned)), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_negative() {

        let cases = vec![

            (-1, vec![0x20]),

            (-10, vec![0x29]),

            (-23, vec![0x36]),

            (-24, vec![0x37]),

            (-25, vec![0x38, 0x18]),

            (-100, vec![0x38, 0x63]),

            (-1000, vec![0x39, 0x03, 0xE7]),

            (-4294967296, vec![0x3A, 0xFF, 0xFF, 0xFF, 0xFF]),

            (

                -4294967297,

                vec![0x3B, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00],

            ),

            (

                i64::MIN,

                vec![0x3B, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF],

            ),

        ];

        for (negative, correct_cbor) in cases {

            assert_eq!(write_return(cbor_int!(negative)), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_byte_string() {

        let cases = vec![

            (vec![], vec![0x40]),

            (

                vec![0x01, 0x02, 0x03, 0x04],

                vec![0x44, 0x01, 0x02, 0x03, 0x04],

            ),

        ];

        for (byte_string, correct_cbor) in cases {

            assert_eq!(write_return(cbor_bytes!(byte_string)), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_text_string() {

        let unicode_3byte = vec![0xE6, 0xB0, 0xB4];

        let cases = vec![

            ("", vec![0x60]),

            ("a", vec![0x61, 0x61]),

            ("IETF", vec![0x64, 0x49, 0x45, 0x54, 0x46]),

            ("\"\\", vec![0x62, 0x22, 0x5C]),

            ("ü", vec![0x62, 0xC3, 0xBC]),

            (

                core::str::from_utf8(&unicode_3byte).unwrap(),

                vec![0x63, 0xE6, 0xB0, 0xB4],

            ),

            ("𐅑", vec![0x64, 0xF0, 0x90, 0x85, 0x91]),

        ];

        for (text_string, correct_cbor) in cases {

            assert_eq!(write_return(cbor_text!(text_string)), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_array() {

        let value_vec: Vec<_> = (1..26).collect();

        let expected_cbor = vec![

            0x98, 0x19, // array of 25 elements

            0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,

            0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x18, 0x18, 0x19,

        ];

        assert_eq!(

            write_return(cbor_array_vec!(value_vec)),

            Some(expected_cbor)

        );

    }

    #[test]

    fn test_write_map() {

        let value_map = cbor_map! {

            0 => "a",

            23 => "b",

            24 => "c",

            u8::MAX as i64 => "d",

            256 => "e",

            u16::MAX as i64 => "f",

            65536 => "g",

            u32::MAX as i64 => "h",

            4294967296_i64 => "i",

            i64::MAX => "j",

            -1 => "k",

            -24 => "l",

            -25 => "m",

            -256 => "n",

            -257 => "o",

            -65537 => "p",

            -4294967296_i64 => "q",

            -4294967297_i64 => "r",

            i64::MIN => "s",

            b"a" => 2,

            b"bar" => 3,

            b"foo" => 4,

            "" => ".",

            "e" => "E",

            "aa" => "AA",

        };

        let expected_cbor = vec![

            0xb8, 0x19, // map of 25 pairs:

            0x00, // key 0

            0x61, 0x61, // value "a"

            0x17, // key 23

            0x61, 0x62, // value "b"

            0x18, 0x18, // key 24

            0x61, 0x63, // value "c"

            0x18, 0xFF, // key 255

            0x61, 0x64, // value "d"

            0x19, 0x01, 0x00, // key 256

            0x61, 0x65, // value "e"

            0x19, 0xFF, 0xFF, // key 65535

            0x61, 0x66, // value "f"

            0x1A, 0x00, 0x01, 0x00, 0x00, // key 65536

            0x61, 0x67, // value "g"

            0x1A, 0xFF, 0xFF, 0xFF, 0xFF, // key 4294967295

            0x61, 0x68, // value "h"

            // key 4294967296

            0x1B, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x61, 0x69, //  value "i"

            // key INT64_MAX

            0x1b, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x61, 0x6a, //  value "j"

            0x20, // key -1

            0x61, 0x6b, // value "k"

            0x37, // key -24

            0x61, 0x6c, // value "l"

            0x38, 0x18, // key -25

            0x61, 0x6d, // value "m"

            0x38, 0xFF, // key -256

            0x61, 0x6e, // value "n"

            0x39, 0x01, 0x00, // key -257

            0x61, 0x6f, // value "o"

            0x3A, 0x00, 0x01, 0x00, 0x00, // key -65537

            0x61, 0x70, // value "p"

            0x3A, 0xFF, 0xFF, 0xFF, 0xFF, // key -4294967296

            0x61, 0x71, // value "q"

            // key -4294967297

            0x3B, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x61, 0x72, //  value "r"

            // key INT64_MIN

            0x3b, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x61, 0x73, //  value "s"

            0x41, b'a', // byte string "a"

            0x02, 0x43, b'b', b'a', b'r', // byte string "bar"

            0x03, 0x43, b'f', b'o', b'o', // byte string "foo"

            0x04, 0x60, // key ""

            0x61, 0x2e, // value "."

            0x61, 0x65, // key "e"

            0x61, 0x45, // value "E"

            0x62, 0x61, 0x61, // key "aa"

            0x62, 0x41, 0x41, // value "AA"

        ];

        assert_eq!(write_return(value_map), Some(expected_cbor));

    }

    #[test]

    fn test_write_map_sorted() {

        let sorted_map = cbor_map! {

            0 => "a",

            1 => "b",

            -1 => "c",

            -2 => "d",

            b"a" => "e",

            b"b" => "f",

            "" => "g",

            "c" => "h",

        };

        let unsorted_map = cbor_map! {

            1 => "b",

            -2 => "d",

            b"b" => "f",

            "c" => "h",

            "" => "g",

            b"a" => "e",

            -1 => "c",

            0 => "a",

        };

        assert_eq!(write_return(sorted_map), write_return(unsorted_map));

    }

    #[test]

    fn test_write_map_with_array() {

        let value_map = cbor_map! {

            "a" => 1,

            "b" => cbor_array![2, 3],

        };

        let expected_cbor = vec![

            0xa2, // map of 2 pairs

            0x61, 0x61, // "a"

            0x01, 0x61, 0x62, // "b"

            0x82, // array with 2 elements

            0x02, 0x03,

        ];

        assert_eq!(write_return(value_map), Some(expected_cbor));

    }

    #[test]

    fn test_write_nested_map() {

        let value_map = cbor_map! {

            "a" => 1,

            "b" => cbor_map! {

                "c" => 2,

                "d" => 3,

            },

        };

        let expected_cbor = vec![

            0xa2, // map of 2 pairs

            0x61, 0x61, // "a"

            0x01, 0x61, 0x62, // "b"

            0xa2, // map of 2 pairs

            0x61, 0x63, // "c"

            0x02, 0x61, 0x64, // "d"

            0x03,

        ];

        assert_eq!(write_return(value_map), Some(expected_cbor));

    }

    #[test]

    fn test_write_tagged() {

        let cases = vec![

            (cbor_tagged!(6, cbor_int!(0x42)), vec![0xc6, 0x18, 0x42]),

            (cbor_tagged!(1, cbor_true!()), vec![0xc1, 0xf5]),

            (

                cbor_tagged!(

                    1000,

                    cbor_map! {

                        "a" => 1,

                        "b" => cbor_array![2, 3],

                    }

                ),

                vec![

                    0xd9, 0x03, 0xe8, 0xa2, // map of 2 pairs

                    0x61, 0x61, // "a"

                    0x01, 0x61, 0x62, // "b"

                    0x82, // array with 2 elements

                    0x02, 0x03,

                ],

            ),

        ];

        for (value, correct_cbor) in cases {

            assert_eq!(write_return(value), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_tagged_nesting_limit() {

        let mut encoded = Vec::new();

        assert_eq!(

            write_nested(cbor_tagged!(0, cbor_int!(0)), &mut encoded, Some(0)),

            Err(EncoderError::TooMuchNesting)

        );

        let mut encoded = Vec::new();

        assert_eq!(

            write_nested(cbor_tagged!(0, cbor_int!(0)), &mut encoded, Some(1)),

            Ok(())

        );

        assert_eq!(encoded, vec![0xc0, 0x00]);

    }

    #[test]

    fn test_write_simple() {

        let cases = vec![

            (cbor_false!(), vec![0xF4]),

            (cbor_true!(), vec![0xF5]),

            (cbor_null!(), vec![0xF6]),

            (cbor_undefined!(), vec![0xF7]),

        ];

        for (value, correct_cbor) in cases {

            assert_eq!(write_return(value), Some(correct_cbor));

        }

    }

    #[test]

    fn test_write_single_levels() {

        let simple_array: Value = cbor_array![2];

        let simple_map: Value = cbor_map! {"b" => 3};

        let positive_cases = vec![

            (cbor_int!(1), 0),

            (cbor_bytes!(vec![0x01, 0x02, 0x03, 0x04]), 0),

            (cbor_text!("a"), 0),

            (cbor_array![], 0),

            (cbor_map! {}, 0),

            (simple_array.clone(), 1),

            (simple_map.clone(), 1),

        ];

        let negative_cases = vec![(simple_array.clone(), 0), (simple_map.clone(), 0)];

        for (value, level) in positive_cases {

            let mut buf = Vec::new();

            let mut writer = Writer::new(&mut buf);

            assert!(writer.encode_cbor(value, Some(level)).is_ok());

        }

        for (value, level) in negative_cases {

            let mut buf = Vec::new();

            let mut writer = Writer::new(&mut buf);

            assert!(!writer.encode_cbor(value, Some(level)).is_ok());

        }

    }

    #[test]

    fn test_write_nested_map_levels() {

        let cbor_map: Value = cbor_map! {

            "a" => 1,

            "b" => cbor_map! {

                "c" => 2,

                "d" => 3,

            },

        };

        let mut buf = Vec::new();

        let mut writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_map.clone(), Some(2)).is_ok());

        assert!(writer.encode_cbor(cbor_map.clone(), None).is_ok());

        writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_map, Some(1)).is_err());

    }

    #[test]

    fn test_write_unbalanced_nested_containers() {

        let cbor_array: Value = cbor_array![

            1,

            2,

            3,

            cbor_map! {

                "a" => 1,

                "b" => cbor_map! {

                    "c" => 2,

                    "d" => 3,

                },

            },

        ];

        let mut buf = Vec::new();

        let mut writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_array.clone(), Some(3)).is_ok());

        writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_array, Some(2)).is_err());

    }

    #[test]

    fn test_write_overly_nested() {

        let cbor_map: Value = cbor_map! {

            "a" => 1,

            "b" => cbor_map! {

                "c" => 2,

                "d" => 3,

                "h" => cbor_map! {

                    "e" => 4,

                    "f" => 5,

                    "g" => cbor_array![

                        6,

                        7,

                        cbor_array![

                            8

                        ]

                    ],

                },

            },

        };

        let mut buf = Vec::new();

        let mut writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_map.clone(), Some(5)).is_ok());

        assert!(writer.encode_cbor(cbor_map.clone(), None).is_ok());

        writer = Writer::new(&mut buf);

        assert!(writer.encode_cbor(cbor_map, Some(4)).is_err());

    }

    #[test]

    fn test_write_default_nesting_boundary() {

        let mut encoded = Vec::new();

        let mut value = cbor_int!(0);

        for _ in 0..127 {

            value = cbor_array![value];

        }

        assert_eq!(write(value.clone(), &mut encoded), Ok(()));

        let mut bytes = vec![0x81; 127]; // 127 nested one-element arrays

        bytes.push(0x00); // 0

        assert_eq!(encoded, bytes);

        assert_eq!(

            write(cbor_array![value], &mut encoded),

            Err(EncoderError::TooMuchNesting)

        );

    }

    #[test]

    fn test_write_nested_unlimited() {

        let mut value = cbor_int!(0);

        for _ in 0..128 {

            value = cbor_array![value];

        }

        let mut bytes = vec![0x81; 128]; // 128 nested one-element arrays

        bytes.push(0x00); // 0

        let mut encoded = Vec::new();

        assert_eq!(write_nested(value, &mut encoded, None), Ok(()));

        assert_eq!(encoded, bytes);

    }

}