class Protocol::HTTP::Header::ETags

The ‘etags` header is used for conditional requests to compare the current version of a resource with previously stored versions. It supports both strong and weak validators, as well as the wildcard character (`*`) to indicate a match for any resource.
The `etags` header represents a list of entity tags (ETags) for resources.

def match?(etag)

@returns [Boolean] whether the specified ETag matches.
@parameter etag [String] the ETag to compare against the `etags` header.

This method returns `true` if the wildcard is present or if the exact ETag is found in the list. Note that this implementation is not strictly compliant with the RFC-specified format.

Checks if the specified ETag matches the `etags` header. 
def match?(etag)
	wildcard? || self.include?(etag)
end

def opposite_tag(etag)

@returns [String] the opposite form of the provided ETag.
@parameter etag [String] the ETag to convert.

Converts a weak tag to its strong counterpart or vice versa. 
def opposite_tag(etag)
	weak_tag?(etag) ? etag[2..-1] : "W/#{etag}"
end

def strong_match?(etag)

@returns [Boolean] whether a strong match is found.
@parameter etag [String] the ETag to compare against the `etags` header.

A strong match requires that the ETag in the header list matches the specified ETag and that neither is a weak validator.

Checks for a strong match with the specified ETag, useful with the `if-match` header. 
def strong_match?(etag)
	wildcard? || (!weak_tag?(etag) && self.include?(etag))
end

def weak_match?(etag)

@returns [Boolean] whether a weak match is found.
@parameter etag [String] the ETag to compare against the `etags` header.

A weak match allows for semantically equivalent content, including weak validators and their strong counterparts.

Checks for a weak match with the specified ETag, useful with the `if-none-match` header. 
def weak_match?(etag)
	wildcard? || self.include?(etag) || self.include?(opposite_tag(etag))
end

def weak_tag?(tag)

@returns [Boolean] whether the tag is weak.
@parameter tag [String] the ETag to check.

Checks if the given ETag is a weak validator. 
def weak_tag?(tag)
	tag&.start_with? "W/"
end

def wildcard?

@returns [Boolean] whether the wildcard is present.

The wildcard character matches any resource version, regardless of its actual value.

Checks if the `etags` header contains the wildcard (`*`) character. 
def wildcard?
	self.include?("*")
end