#ifndef INCLUDED_C_TARJANSCC_H
#define INCLUDED_C_TARJANSCC_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*          low;         /* low[v] = low link of vertex v */
    c_size_t*          stack;       /* Explicit vertex stack buffer for component mapping tracking */
    c_size_t           stack_size;  /* Current active elements size in stack tracker */
    c_bool_t*          on_stack;    /* Quick boolean lookup mapping for stack memberships */
    c_size_t           pre_counter; /* Preorder index sequencing index variable counter */
    c_size_t           count;       /* Total number of strongly connected components discovered */
    c_size_t           V;
    c_Allocator_t      allocator;   /* Deep copy of the user-provided allocator */
} c_TarjanSCC_t;

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

/**
 * @brief Computes strongly connected components for the specified digraph using Tarjan's algorithm.
 * @param allocator Explicit allocator context used to allocate internal routing arrays
 */
c_err_t c_TarjanSCC_Init(c_TarjanSCC_t* self, c_Digraph_t* graph, c_Allocator_t* allocator);

/**
 * @brief Releases internal tracking buffers
 */
void c_TarjanSCC_Destroy(c_TarjanSCC_t* self);

/**
 * @brief Are vertices 'v' and 'w' strongly connected (belong to the same SCC)?
 */
C_STATIC_FORCE_INLINE
c_bool_t c_TarjanSCC_StronglyConnected(c_TarjanSCC_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_TarjanSCC_GetId(const c_TarjanSCC_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_TarjanSCC_GetCount(const c_TarjanSCC_t* self) {
    return self ? self->count : 0;
}

#endif /*INCLUDED_C_TARJANSCC_H*/