#ifndef YAML_H
#define YAML_H

#include <stdlib.h>

typedef enum {
    YAML_TYPE_STRING, /**< A value that represents a string. */
    YAML_TYPE_NUMBER, /**< A value that represents a number. */
    YAML_TYPE_OBJECT, /**< A value that represents an object. */
    YAML_TYPE_ARRAY,  /**< A value that represents an array. */
    YAML_TYPE_TRUE,   /**< A value that represents true. */
    YAML_TYPE_FALSE,  /**< A value that represents false. */
    YAML_TYPE_NULL,   /**< A value that represents null. */
} yaml_type_t;

typedef struct {
    void *data;
    yaml_type_t type;
} yaml_value_t;

typedef struct {
    const char *data;
    size_t length;
} yaml_string_t;

typedef struct {
    const char *data;
    size_t length;
} yaml_number_t;

typedef struct yaml_object_field_s {
    yaml_string_t *name;
    yaml_value_t *value;

    struct yaml_object_field_s *next;
} yaml_object_field_t;

typedef struct {
    yaml_object_field_t *head;
    size_t count;
} yaml_object_t;

typedef struct yaml_array_element_s {
    yaml_value_t *value;

    struct yaml_array_element_s *next;
} yaml_array_element_t;

typedef struct {
    yaml_array_element_t *head;
    size_t count;
} yaml_array_t;

/**
 * Parse a UTF-8 encoded string into a value object.
 *
 * Returns `NULL` if parsing fails.
 */
yaml_value_t *yaml_parse(const void *, size_t);

/**
 * Traverse the tree to retrieve a specific sub-value from a root value.
 *
 * Returns `NULL` if the requested sub-value does not exist.
 */
yaml_value_t *yaml_get(const yaml_value_t *, const char *);

/**
 * Access a value object as a string.
 *
 * Returns `NULL` if the value is not a string.
 */
yaml_string_t *yaml_value_as_string(const yaml_value_t *);

/**
 * Access a value object as a number.
 *
 * Returns `NULL` if the value is not a number.
 */
yaml_number_t *yaml_value_as_number(const yaml_value_t *);

/**
 * Access a value object as an object.
 *
 * Returns `NULL` if the value is not an object.
 */
yaml_object_t *yaml_value_as_object(const yaml_value_t *);

/**
 * Access a value object as an array.
 *
 * Returns `NULL` if the value is not an array.
 */
yaml_array_t *yaml_value_as_array(const yaml_value_t *);

/**
 * Return a string describing the most recently encountered error.
 *
 * Returns `NULL` if no error has been encountered.
 */
const char *yaml_error(void);

#endif /* YAML_H */

#ifdef YAML_IMPLEMENTATION

char error_message[4096];

yaml_value_t *yaml_parse(const void *content, size_t length) {
    /* TODO */
    return NULL;
}

yaml_value_t *yaml_get(const yaml_value_t *root, const char *path) {
    /* TODO */
    return NULL;
}

yaml_string_t *yaml_value_as_string(const yaml_value_t *value) {
    /* TODO */
    return NULL;
}

yaml_number_t *yaml_value_as_number(const yaml_value_t *value) {
    /* TODO */
    return NULL;
}

yaml_object_t *yaml_object_as_object(const yaml_value_t *value) {
    /* TODO */
    return NULL;
}

yaml_array_t *yaml_object_as_array(const yaml_value_t *value) {
    /* TODO */
    return NULL;
}

const char *yaml_error(void) {
    if (error_message[0] == '\0') return NULL;
    return error_message;
}

#endif /* YAML_IMPLEMENTATION */