#ifndef INCLUDED_C_BREADTHFIRSTDIRECTEDPATHS_H
#define INCLUDED_C_BREADTHFIRSTDIRECTEDPATHS_H

#ifndef INCLUDED_C_DIGRAPH_H
#include <c_Digraph.h>
#endif /*INCLUDED_C_DIGRAPH_H*/

#ifndef INCLUDED_C_VERTEXIDLIST_H
#include <c_VertexIdList.h>
#endif /*INCLUDED_C_VERTEXIDLIST_H*/


/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

typedef struct {
    c_bool_t*      marked;      /* Visited tracking array (size of graph->V) */
    c_size_t*      edge_to;     /* edge_to[w] = last edge on shortest path from s to w */
    c_size_t*      dist_to;     /* dist_to[w] = number of edges on shortest path from s to w */
    c_size_t       s;           /* Source vertex */
    c_Allocator_t  allocator;   /* Deep copy of the user-provided allocator */
} c_BreadthFirstDirectedPaths_t;

/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

/**
 * @brief Computes shortest directed paths from a single source vertex 's' using BFS
 * @param allocator Explicit allocator context used to allocate internal routing arrays
 */
c_err_t c_BreadthFirstDirectedPaths_Init(c_BreadthFirstDirectedPaths_t* self, const c_Digraph_t* graph, c_size_t s, c_Allocator_t* allocator);

/**
 * @brief Releases internal tracking buffers
 */
void c_BreadthFirstDirectedPaths_Destroy(c_BreadthFirstDirectedPaths_t* self);

/**
 * @brief Is there a directed path from the source 's' to vertex 'v'?
 */
C_STATIC_FORCE_INLINE
c_bool_t c_BreadthFirstDirectedPaths_HasPathTo(c_BreadthFirstDirectedPaths_t* self, c_size_t v, c_size_t total_V) {
    if (!self || !self->marked || v >= total_V) return C_FALSE;
    return self->marked[v];
}

/**
 * @brief Returns the number of edges in a shortest path from the source 's' to vertex 'v'
 * @return Distance value, or C_SIZE_MAX if unreachable / parameter error
 */
C_STATIC_FORCE_INLINE
c_size_t c_BreadthFirstDirectedPaths_DistTo(c_BreadthFirstDirectedPaths_t* self, c_size_t v, c_size_t total_V) {
    if (!self || v >= total_V || !self->marked[v]) return C_SIZE_MAX;
    return self->dist_to[v];
}

/**
 * @brief Reconstructs the exact shortest path from source 's' to vertex 'v' and appends it to out_path
 */
c_err_t c_BreadthFirstDirectedPaths_PathTo(c_BreadthFirstDirectedPaths_t* self, c_size_t v, c_size_t total_V, c_VertexIdList_t* out_path);


#endif /*INCLUDED_C_BREADTHFIRSTDIRECTEDPATHS_H*/