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#ifndef PGAGROAL_UTF8_H
#define PGAGROAL_UTF8_H

#include <stdbool.h>
#include <stddef.h>

/**
 * Counts the number of Unicode code points in a UTF-8 byte sequence.
 * @param buf The UTF-8 byte buffer.
 * @param len The length of the buffer in bytes.
 * @return The number of code points, or -1 on error.
 */
size_t
pgagroal_utf8_char_length(const unsigned char* buf, size_t len);

/**
 * Checks if a string contains only ASCII characters (0-127).
 * @param str The input string.
 * @param len The length of the string in bytes.
 * @return true if all characters are ASCII, false otherwise.
 */
bool
pgagroal_is_ascii(const char* str, size_t len);

/**
 * Validates if the entire byte buffer contains valid UTF-8.
 * @param buf The UTF-8 byte buffer.
 * @param len The length of the buffer in bytes.
 * @return true if valid UTF-8, false otherwise.
 */
bool
pgagroal_utf8_valid(const unsigned char* buf, size_t len);

/**
 * Validates a single UTF-8 sequence (1-4 bytes) according to RFC 3629.
 * Checks for overlong encodings, surrogate pairs, and Unicode range limits.
 *
 * Derived from pg_utf8_islegal in PostgreSQL:
 * https://www.postgresql.org/about/licence/
 * Licensed under the PostgreSQL License.
 *
 * @param source pointer to the UTF-8 sequence
 * @param length expected length of the sequence (1-4)
 * @return true if the sequence is valid, false otherwise
 */
bool
pgagroal_utf8_sequence_valid(const unsigned char* source, int length);

/**
 * Get the expected byte length of a UTF-8 sequence from its first byte.
 * @param first_byte the first byte of the UTF-8 sequence
 * @return sequence length (1-4) or -1 if invalid start byte
 */
int
pgagroal_utf8_sequence_length(unsigned char first_byte);

#endif /* UTF8_H */