#ifndef INCLUDED_C_NONRECURSIVEGABOWSCC_H
#define INCLUDED_C_NONRECURSIVEGABOWSCC_H

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


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

typedef struct {
    c_bool_t*          marked;       /* Visited tracking array (size of graph->V) */
    c_size_t*          id;           /* id[v] = component identifier containing v (0 to count-1) */
    c_size_t*          pre;          /* pre[v] = preorder index of vertex v */
    c_size_t*          scc_stack;    /* Stack to keep track of vertices in the current SCC candidate */
    c_size_t           scc_stack_sz; /* Size of scc_stack */
    c_size_t*          path_stack;   /* Stack to determine root of strongly connected components */
    c_size_t           path_stack_sz;/* Size of path_stack */
    c_size_t           pre_counter;  /* Preorder index sequencing counter */
    c_size_t           count;        /* Total number of strongly connected components discovered */
    c_size_t           V;            /* Stored vertex count for safe boundary check lookups */
    c_Allocator_t      allocator;    /* Deep copy of the user-provided allocator */
} c_NonrecursiveGabowSCC_t;

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

/**
 * @brief Non-recursively computes strongly connected components for the specified digraph using Gabow's algorithm.
 * @param allocator Explicit allocator context used to allocate internal routing arrays
 */
c_err_t c_NonrecursiveGabowSCC_Init(c_NonrecursiveGabowSCC_t* self, c_Digraph_t* graph, c_Allocator_t* allocator);

/**
 * @brief Releases internal tracking buffers
 */
void c_NonrecursiveGabowSCC_Destroy(c_NonrecursiveGabowSCC_t* self);

/**
 * @brief Are vertices 'v' and 'w' strongly connected (belong to the same SCC)?
 */
C_STATIC_FORCE_INLINE
c_bool_t c_NonrecursiveGabowSCC_StronglyConnected(c_NonrecursiveGabowSCC_t* self, c_size_t v, c_size_t w) {
    if (!self || !self->id || v >= self->V || w >= self->V) return C_FALSE;
    return self->id[v] == self->id[w];
}

/**
 * @brief Returns the component id containing vertex 'v'
 * @return Component integer ID (0 to count-1), or C_SIZE_MAX on boundary check failures
 */
C_STATIC_FORCE_INLINE
c_size_t c_NonrecursiveGabowSCC_GetId(const c_NonrecursiveGabowSCC_t* self, c_size_t v) {
    if (!self || !self->id || v >= self->V) return C_SIZE_MAX;
    return self->id[v];
}

/**
 * @brief Returns the total number of strongly connected components
 */
C_STATIC_FORCE_INLINE
c_size_t c_NonrecursiveGabowSCC_GetCount(const c_NonrecursiveGabowSCC_t* self) {
    return self ? self->count : 0;
}

#endif /*INCLUDED_C_NONRECURSIVEGABOWSCC_H*/