// Copyright (c) 2022, 2024 blackshirt. All rights reserved.
// Use of this source code is governed by a MIT License
// that can be found in the LICENSE file.
module asn1

// default_ia5string_tag is the default tag of ASN.1 IA5STRING type.
pub const default_ia5string_tag = Tag{.universal, false, int(TagType.ia5string)}

// ASN.1 IA5String type handling routine.
// IA5String is a standard ASCII characters
pub struct IA5String {
pub:
    value string
}

// new creates a IA5String element from string s.
pub fn IA5String.new(s string) !IA5String {
    if !valid_ia5string(s) {
        return error('IA5String: contains non-ascii chars')
    }
    return IA5String{
        value: s
    }
}

// tag returns the tag of IA5String type element.
pub fn (v IA5String) tag() Tag {
    return default_ia5string_tag
}

// payload returns the payload of IA5String type element.
pub fn (v IA5String) payload() ![]u8 {
    if !v.value.is_ascii() {
        return error('IA5String: contains non-ascii chars')
    }
    return v.value.bytes()
}

fn (v IA5String) str() string {
    if v.value.len == 0 {
        return 'IA5String (<empty>)'
    }
    return 'IA5String (${v.value})'
}

fn IA5String.parse(mut p Parser) !IA5String {
    tag := p.read_tag()!
    if !tag.equal(default_ia5string_tag) {
        return error('Bad Ia5String tag')
    }
    length := p.read_length()!
    bytes := p.read_bytes(length)!

    res := IA5String.from_bytes(bytes)!

    return res
}

fn IA5String.decode(bytes []u8) !(IA5String, int) {
    bs, next := IA5String.decode_with_rule(bytes, .der)!
    return bs, next
}

fn IA5String.decode_with_rule(bytes []u8, rule EncodingRule) !(IA5String, int) {
    tag, length_pos := Tag.decode_with_rule(bytes, 0, rule)!
    if !tag.equal(default_ia5string_tag) {
        return error('Unexpected non-ia5string tag')
    }
    length, content_pos := Length.decode_with_rule(bytes, length_pos, rule)!

    // if the length is 0, this mean if the payload is empty
    // otherwise, check for bound
    content := if length == 0 {
        []u8{}
    } else {
        if content_pos >= bytes.len || content_pos + length > bytes.len {
            return error('IA5String: truncated payload bytes')
        }
        unsafe { bytes[content_pos..content_pos + length] }
    }

    result := IA5String.from_bytes(content)!
    next := content_pos + length

    return result, next
}

// from_bytes creates a new IA5String from bytes b
fn IA5String.from_bytes(b []u8) !IA5String {
    if b.any(it < u8(` `) || it > u8(`~`)) {
        return error('IA5String: bytes contains non-ascii chars')
    }
    return IA5String{
        value: b.bytestr()
    }
}

// Utility function
fn valid_ia5string(s string) bool {
    return s.is_ascii()
}