#include <stdio.h>
#include <SWI-Prolog.h>
#include <gvc.h>
#include "graphviz_swiprolog.h"

static GVC_t *gvc;

#define PL_check(result) \
    if (!(result)) { \
        PL_fail; \
    }

int
PL_get_desc(term_t desc_term, Agdesc_t *desc) {
    char *desc_string;
    PL_check(PL_get_atom_chars(desc_term, &desc_string));
    if (strcmp(desc_string, "undirected") == 0) {
        *desc = Agundirected;
    }
    else if (strcmp(desc_string, "strict_undirected") == 0) {
        *desc = Agstrictundirected;
    }
    else if (strcmp(desc_string, "directed") == 0) {
        *desc = Agdirected;
    }
    else if (strcmp(desc_string, "strict_directed") == 0) {
        *desc = Agstrictdirected;
    }
    else {
        PL_fail;
    }
    PL_succeed;
}

int
PL_get_graph(term_t graph_term, Agraph_t **graph) {
    return PL_get_pointer(graph_term, (void **) graph);
}

int
PL_get_kind(term_t desc_term, int *kind) {
    char *desc_string;
    PL_check(PL_get_atom_chars(desc_term, &desc_string));
    if (strcmp(desc_string, "graph") == 0) {
        *kind = AGRAPH;
    }
    else if (strcmp(desc_string, "node") == 0) {
        *kind = AGNODE;
    }
    else if (strcmp(desc_string, "out_edge") == 0) {
        *kind = AGOUTEDGE;
    }
    else if (strcmp(desc_string, "in_edge") == 0) {
        *kind = AGINEDGE;
    }
    else if (strcmp(desc_string, "edge") == 0) {
        *kind = AGEDGE;
    }
    else {
        PL_fail;
    }
    PL_succeed;
}

int
PL_get_node(term_t graph_term, Agnode_t **node) {
    return PL_get_pointer(graph_term, (void **) node);
}

int
PL_unify_graph_or_close(term_t graph_term, Agraph_t *graph) {
    int result = PL_unify_pointer(graph_term, graph);
    if (!result) {
        agclose(graph);
    }
    return result;
}

static foreign_t
pl_agattr(
    term_t graph_term, term_t kind_term, term_t name_term,
    term_t value_term, term_t sym_term
) {
    Agraph_t *graph;
    int kind;
    char *name;
    char *value;
    Agsym_t *sym;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_kind(kind_term, &kind));
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(PL_get_atom_chars(value_term, &value));
    PL_check(sym = agattr(graph, kind, name, value));
    PL_check(PL_unify_pointer(sym_term, sym));
    PL_succeed;
}

static foreign_t
pl_agclose(term_t graph_term) {
    Agraph_t *graph;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(!agclose(graph));
    PL_succeed;
}

static foreign_t
pl_agedge(
    term_t graph_term, term_t node0_term, term_t node1_term, term_t name_term,
    term_t create_flag_term, term_t edge_term
) {
    Agraph_t *graph;
    Agnode_t *node0;
    Agnode_t *node1;
    char *name;
    int create_flag;
    Agedge_t *edge;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_node(node0_term, &node0));
    PL_check(PL_get_node(node1_term, &node1));
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(PL_get_bool(create_flag_term, &create_flag));
    PL_check(edge = agedge(graph, node0, node1, name, create_flag));
    PL_check(PL_unify_pointer(edge_term, edge));
    PL_succeed;

}

static foreign_t
pl_agget(term_t object_term, term_t name_term, term_t value_term) {
    void *object;
    char *name;
    char *value;
    PL_check(PL_get_pointer(object_term, &object));
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(value = agget(object, name));
    PL_check(PL_unify_atom_chars(value_term, value));
    PL_succeed;
}

static foreign_t
pl_agnode(
    term_t graph_term, term_t name_term, term_t create_flag_term,
    term_t node_term
) {
    Agraph_t *graph;
    char *name;
    int create_flag;
    Agnode_t *node;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(PL_get_bool(create_flag_term, &create_flag));
    PL_check(node = agnode(graph, name, create_flag));
    PL_check(PL_unify_pointer(node_term, node));
    PL_succeed;

}

static foreign_t
pl_agread(term_t filename_term, term_t graph_term) {
    char *filename;
    FILE *file;
    Agraph_t *graph;
    PL_check(PL_get_atom_chars(filename_term, &filename));
    PL_check(file = fopen(filename, "r"));
    PL_check(graph = agread(file, 0));
    PL_check(!fclose(file));
    PL_check(PL_unify_graph_or_close(graph_term, graph));
    PL_succeed;
}

static foreign_t
pl_agopen(term_t name_term, term_t desc_term, term_t graph_term) {
    char *name;
    char *graph_type;
    Agdesc_t desc;
    Agraph_t *graph;
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(PL_get_desc(desc_term, &desc));
    PL_check(graph = agopen(name, desc, 0));
    PL_check(PL_unify_graph_or_close(graph_term, graph));
    PL_succeed;
}

static foreign_t
pl_agset(term_t object_term, term_t name_term, term_t value_term) {
    void *object;
    char *name;
    char *value;
    PL_check(PL_get_pointer(object_term, &object));
    PL_check(PL_get_atom_chars(name_term, &name));
    PL_check(PL_get_atom_chars(value_term, &value));
    PL_check(!agset(object, name, value));
    PL_succeed;
}

static foreign_t
pl_agwrite(term_t graph_term, term_t filename_term) {
    Agraph_t *graph;
    char *filename;
    FILE *file;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_atom_chars(filename_term, &filename));
    PL_check(file = fopen(filename, "w"));
    PL_check(!agwrite(graph, file));
    PL_check(!fclose(file));
    PL_succeed;
}

static foreign_t
pl_gvFreeLayout(term_t graph_term) {
    Agraph_t *graph;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(!gvFreeLayout(gvc, graph));
    PL_succeed;
}

static foreign_t
pl_gvLayout(term_t graph_term, term_t engine_term) {
    Agraph_t *graph;
    char *engine;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_atom_chars(engine_term, &engine));
    PL_check(!gvLayout(gvc, graph, engine));
    PL_succeed;
}

static foreign_t
pl_gvRenderFilename(
    term_t graph_term, term_t format_term, term_t filename_term
) {
    Agraph_t *graph;
    char *format;
    char *filename;
    FILE *file;
    PL_check(PL_get_graph(graph_term, &graph));
    PL_check(PL_get_atom_chars(format_term, &format));
    PL_check(PL_get_atom_chars(filename_term, &filename));
    PL_check(!gvRenderFilename(gvc, graph, format, filename));
    PL_succeed;
}

PL_extension graphviz_predicates[] = {
    { "agattr", 5, pl_agattr, 0 },
    { "agclose", 1, pl_agclose, 0 },
    { "agedge", 6, pl_agedge, 0 },
    { "agget", 3, pl_agget, 0 },
    { "agnode", 4, pl_agnode, 0 },
    { "agopen", 3, pl_agopen, 0 },
    { "agread", 2, pl_agread, 0 },
    { "agset", 3, pl_agset, 0 },
    { "agwrite", 2, pl_agwrite, 0 },
    { "gvFreeLayout", 1, pl_gvFreeLayout, 0 },
    { "gvLayout", 2, pl_gvLayout, 0 },
    { "gvRenderFilename", 3, pl_gvRenderFilename, 0 },
    { NULL, 0, NULL, 0 }
};

install_t
install_graphviz_swiprolog(void) {
    gvc = gvContext();
    PL_register_extensions(graphviz_predicates);
}