seam-cli 0.5.38

/* src/cli/core/src/build/route/fnv.rs */

const FNV_OFFSET: u32 = 2_166_136_261;
const FNV_PRIME: u32 = 16_777_619;

/// Standard FNV-1a 32-bit hash.
pub(crate) fn fnv1a_32(input: &str) -> u32 {
	let mut hash = FNV_OFFSET;
	for byte in input.bytes() {
		hash ^= byte as u32;
		hash = hash.wrapping_mul(FNV_PRIME);
	}
	hash
}

/// Route pattern -> 8 hex chars (full 32-bit FNV-1a).
pub(crate) fn route_hash(pattern: &str) -> String {
	format!("{:08x}", fnv1a_32(pattern))
}

/// Content string -> 4 hex chars (lower 16 bits of FNV-1a).
pub(crate) fn content_hash(data: &str) -> String {
	format!("{:04x}", fnv1a_32(data) & 0xFFFF)
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn fnv1a_deterministic() {
		assert_eq!(fnv1a_32("hello"), fnv1a_32("hello"));
	}

	#[test]
	fn fnv1a_different_inputs() {
		assert_ne!(fnv1a_32("hello"), fnv1a_32("world"));
	}

	#[test]
	fn fnv1a_empty_string() {
		assert_eq!(fnv1a_32(""), FNV_OFFSET);
	}

	#[test]
	fn route_hash_length() {
		let h = route_hash("/");
		assert_eq!(h.len(), 8);
		assert!(h.chars().all(|c| c.is_ascii_hexdigit()));
	}

	#[test]
	fn content_hash_length() {
		let h = content_hash("hello=world");
		assert_eq!(h.len(), 4);
		assert!(h.chars().all(|c| c.is_ascii_hexdigit()));
	}

	#[test]
	fn route_hash_known_values() {
		// Verify specific patterns produce consistent output
		let h1 = route_hash("/");
		let h2 = route_hash("/dashboard");
		assert_ne!(h1, h2);
		// Re-run produces same result
		assert_eq!(h1, route_hash("/"));
	}
}