import time
import x.encoding.asn1

// This Benchmark was performs serialization and deserialization from ASN.1 schema defined as:
// ```asn.1
// Example ::= SEQUENCE {
//    greeting    UTF8String,
//    answer      INTEGER,
//    type        [1] EXPLICIT OBJECT IDENTIFIER
// }
// ```
struct Example {
    greeting asn1.Utf8String
    answer   asn1.Integer
    // you can tag your struct fields with supported options.
    tipe asn1.ObjectIdentifier @[context_specific: 1; explicit; inner: 6]
}

fn (ex Example) tag() asn1.Tag {
    return asn1.default_sequence_tag
}

// you can build your payload manually or use `asn1.make_payload`, but be aware,
// if your structure contains generics, its may not work (currently).
// Updates: Thank to @felipensp. He has a great job to resolve this issue.
// Its was resolved in [22724](https://github.com/vlang/v/pull/22724)
fn (ex Example) payload() ![]u8 {
    kd := asn1.KeyDefault(map[string]asn1.Element{})
    payload := asn1.make_payload[Example](ex, kd)!

    return payload
}

// You can write custom decode routines for the Example structure. This is only one
// example, but its possible to do this in other ways with help from this module such
// as using the `Parser` codec.
fn Example.decode(bytes []u8) !Example {
    // just call raw .decode on bytes
    // for example, its should produce sequence type.
    elem := asn1.decode(bytes)!
    assert elem.tag().equal(asn1.default_sequence_tag) // should true

    // cast produced element into Sequence type and get the fields.
    seq := elem.into_object[asn1.Sequence]()!
    fields := seq.fields()

    // and then, turn every field into desired objects based on your schema.
    // first two field is not wrapped element, so just turn into real object.
    greeting := fields[0].into_object[asn1.Utf8String]()!
    answer := fields[1].into_object[asn1.Integer]()!

    // the third field is a context_specific wrapped element, just unwrap it with the
    // same options used to encode.
    oid_tipe := fields[2].unwrap_with_options('context_specific:1;explicit; inner:6')!
    tipe := oid_tipe.into_object[asn1.ObjectIdentifier]()!

    // then build your Example struct
    ex := Example{
        greeting: greeting
        answer:   answer
        tipe:     tipe
    }
    return ex
}

fn main() {
    expected_output := [u8(0x30), 18, u8(12), 5, 72, 101, 108, 108, 111, u8(2), 1, 42, u8(0xA1),
        6, 6, 4, 43, 6, 1, 3]
    ex := Example{
        greeting: asn1.Utf8String.new('Hello')!
        answer:   asn1.Integer.from_int(42)
        tipe:     asn1.ObjectIdentifier.from_ints([1, 3, 6, 1, 3])!
    }
    iterations := 1000

    println('Benchmarking ASN.1 encode...')
    mut total_enc_time := i64(0)
    for _ in 0 .. iterations {
        sw := time.new_stopwatch()
        _ := asn1.encode(ex) or { panic(err) }
        elapsed := sw.elapsed().microseconds()
        total_enc_time += elapsed
    }
    avg_enc_time := total_enc_time / iterations
    println('Average example encode time: ${avg_enc_time} µs')

    println('Benchmarking ASN.1 decode (with asn1.decode)...')
    mut total_dec_time := i64(0)
    for _ in 0 .. iterations {
        sw := time.new_stopwatch()
        _ := asn1.decode(expected_output) or { panic(err) }
        elapsed := sw.elapsed().microseconds()
        total_dec_time += elapsed
    }
    avg_asn1dec_time := total_dec_time / iterations
    println('Average (asn1.decode) decode time: ${avg_asn1dec_time} µs')

    println('Benchmarking ASN.1 decode with Example.decode)...')
    mut total_exdec_time := i64(0)
    for _ in 0 .. iterations {
        sw := time.new_stopwatch()
        _ := asn1.decode(expected_output) or { panic(err) }
        elapsed := sw.elapsed().microseconds()
        total_exdec_time += elapsed
    }
    avg_exdec_time := total_exdec_time / iterations
    println('Average (Example.decode) decode time: ${avg_exdec_time} µs')
}