#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>

// PCRE
#include <pcre.h>

#include "r3.h"
#include "r3_str.h"
#include "str_array.h"
#include "zmalloc.h"

// String value as the index http://judy.sourceforge.net/doc/JudySL_3x.htm


static int strndiff(char * d1, char * d2, unsigned int n) {
    char * o = d1;
    while ( *d1 == *d2 && n-- > 0 ) {
        d1++;
        d2++;
    }
    return d1 - o;
}

static int strdiff(char * d1, char * d2) {
    char * o = d1;
    while( *d1 == *d2 ) {
        d1++;
        d2++;
    }
    return d1 - o;
}


/**
 * Create a node object
 */
node * r3_tree_create(int cap) {
    node * n = (node*) zmalloc( sizeof(node) );

    n->edges = (edge**) zmalloc( sizeof(edge*) * cap );
    n->edge_len = 0;
    n->edge_cap = cap;

    n->routes = NULL;
    n->route_len = 0;
    n->route_cap = 0;

    n->endpoint = 0;
    n->combined_pattern = NULL;
    n->pcre_pattern = NULL;
    n->pcre_extra = NULL;
    return n;
}

void r3_tree_free(node * tree) {
    for (int i = 0 ; i < tree->edge_len ; i++ ) {
        if (tree->edges[i]) {
            r3_edge_free(tree->edges[ i ]);
        }
    }
    zfree(tree->edges);
    zfree(tree->routes);

    if (tree->pcre_pattern) {
        pcre_free(tree->pcre_pattern);
    }
#ifdef PCRE_STUDY_JIT_COMPILE
    if (tree->pcre_extra) {
        pcre_free_study(tree->pcre_extra);
    }
#endif
    zfree(tree->combined_pattern);
    zfree(tree);
    tree = NULL;
}

edge * r3_node_connectl(node * n, char * pat, int len, int dupl, node *child) {
    // find the same sub-pattern, if it does not exist, create one
    edge * e;

    e = r3_node_find_edge(n, pat);
    if (e) {
        return e;
    }

    if (dupl) {
        pat = zstrndup(pat, len);
    }
    e = r3_edge_create(pat, len, child);
    r3_node_append_edge(n, e);
    return e;
}

void r3_node_append_edge(node *n, edge *e) {
    if (n->edges == NULL) {
        n->edge_cap = 3;
        n->edges = zmalloc(sizeof(edge) * n->edge_cap);
    }
    if (n->edge_len >= n->edge_cap) {
        n->edge_cap *= 2;
        edge ** p = zrealloc(n->edges, sizeof(edge) * n->edge_cap);
        if(p) {
            n->edges = p;
        }
    }
    n->edges[ n->edge_len++ ] = e;
}

edge * r3_node_find_edge(node * n, char * pat) {
    edge * e;
    for (int i = 0 ; i < n->edge_len ; i++ ) {
        e = n->edges[i];
        if ( strcmp(e->pattern, pat) == 0 ) {
            return e;
        }
    }
    return NULL;
}

void r3_tree_compile(node *n)
{
    bool use_slug = r3_node_has_slug_edges(n);
    if ( use_slug ) {
        r3_tree_compile_patterns(n);
    } else {
        // use normal text matching...
        n->combined_pattern = NULL;
    }

    for (int i = 0 ; i < n->edge_len ; i++ ) {
        r3_tree_compile(n->edges[i]->child);
    }
}


/**
 * This function combines ['/foo', '/bar', '/{slug}'] into (/foo)|(/bar)|/([^/]+)}
 *
 */
void r3_tree_compile_patterns(node * n) {
    char * cpat;
    char * p;

    cpat = zcalloc(sizeof(char) * 128);
    if (cpat==NULL)
        return;

    p = cpat;

    strncat(p, "^", 1);
    p++;

    edge *e = NULL;
    int opcode_cnt =  0;
    for ( int i = 0 ; i < n->edge_len ; i++ ) {
        e = n->edges[i];

        if ( e->opcode )
            opcode_cnt++;

        if ( e->has_slug ) {
            // compile "foo/{slug}" to "foo/[^/]+"
            char * slug_pat = slug_compile(e->pattern, e->pattern_len);
            strcat(p, slug_pat);
        } else {
            strncat(p++,"(", 1);

            strncat(p, e->pattern, e->pattern_len);
            p += e->pattern_len;

            strncat(p++,")", 1);
        }

        if ( i + 1 < n->edge_len && n->edge_len > 1 ) {
            strncat(p++,"|",1);
        }
    }

    info("pattern: %s\n",cpat);

    // if all edges use opcode, we should skip the combined_pattern.
    if ( opcode_cnt == n->edge_len ) {
        // zfree(cpat);
        n->compare_type = NODE_COMPARE_OPCODE;
    } else {
        n->compare_type = NODE_COMPARE_PCRE;
    }

    n->combined_pattern = cpat;

    const char *error;
    int erroffset;
    unsigned int option_bits = 0;

    if (n->pcre_pattern) {
        pcre_free(n->pcre_pattern);
    }
    n->pcre_pattern = pcre_compile(
            n->combined_pattern,              /* the pattern */
            option_bits,                                /* default options */
            &error,               /* for error message */
            &erroffset,           /* for error offset */
            NULL);                /* use default character tables */
    if (n->pcre_pattern == NULL) {
        printf("PCRE compilation failed at offset %d: %s, pattern: %s\n", erroffset, error, n->combined_pattern);
        return;
    }
#ifdef PCRE_STUDY_JIT_COMPILE
    if (n->pcre_extra) {
        pcre_free_study(n->pcre_extra);
    }
    n->pcre_extra = pcre_study(n->pcre_pattern, 0, &error);
    if (n->pcre_extra == NULL) {
        printf("PCRE study failed at offset %s\n", error);
        return;
    }
#endif
}


match_entry * match_entry_createl(char * path, int path_len) {
    match_entry * entry = zmalloc(sizeof(match_entry));
    if(!entry)
        return NULL;
    entry->vars = str_array_create(3);
    entry->path = path;
    entry->path_len = path_len;
    entry->data = NULL;
    return entry;
}

void match_entry_free(match_entry * entry) {
    str_array_free(entry->vars);
    zfree(entry);
}



/**
 * This function matches the URL path and return the left node
 *
 * r3_tree_matchl returns NULL when the path does not match. returns *node when the path matches.
 *
 * @param node         n        the root of the tree
 * @param char*        path     the URL path to dispatch
 * @param int          path_len the length of the URL path.
 * @param match_entry* entry match_entry is used for saving the captured dynamic strings from pcre result.
 */
node * r3_tree_matchl(const node * n, char * path, int path_len, match_entry * entry) {
    info("try matching: %s\n", path);

    edge *e;
    char rc;
    unsigned short i;
    unsigned short ov_cnt;
    unsigned short restlen;
    char *pp;
    char *pp_end = path + path_len;

    char *substring_start = NULL;
    int   substring_length = 0;

    if (n->compare_type == NODE_COMPARE_OPCODE) {
        for (i = 0; i < n->edge_len ; i++ ) {
            pp = path;
            e = n->edges[i];
            switch(e->opcode) {
                case OP_EXPECT_NOSLASH:
                    while (*pp != '/' && pp < pp_end) pp++;
                    break;
                case OP_EXPECT_MORE_ALPHA:
                    while ( isalpha(*pp) && pp < pp_end) pp++;
                    break;
                case OP_EXPECT_MORE_DIGITS:
                    while ( isdigit(*pp) && pp < pp_end) pp++;
                    break;
                case OP_EXPECT_MORE_WORDS:
                    while ( (isdigit(*pp) || isalpha(*pp)) && pp < pp_end) pp++;
                    break;
                case OP_EXPECT_NODASH:
                    while (*pp != '-' && pp < pp_end) pp++;
                    break;
            }
            // check match
            if ( (pp - path) > 0) {
                restlen = pp_end - pp;
                if (entry) {
                    str_array_append(entry->vars , zstrndup(path, pp - path));
                }
                if (restlen == 0) {
                    return e->child && e->child->endpoint > 0 ? e->child : NULL;
                }
                return r3_tree_matchl(e->child, pp, pp_end - pp, entry);
            }
        }
    }

    // if the pcre_pattern is found, and the pointer is not NULL, then it's
    // pcre pattern node, we use pcre_exec to match the nodes
    if (n->pcre_pattern) {
        info("pcre matching %s on %s\n", n->combined_pattern, path);
        ov_cnt = (1 + n->edge_len) * 3;
        int ov[ ov_cnt ];

        rc = pcre_exec(
                n->pcre_pattern, /* the compiled pattern */
                n->pcre_extra,
                path,         /* the subject string */
                path_len,     /* the length of the subject */
                0,            /* start at offset 0 in the subject */
                0,            /* default options */
                ov,           /* output vector for substring information */
                ov_cnt);      /* number of elements in the output vector */

        // does not match all edges, return NULL;
        if (rc < 0) {
#ifdef DEBUG
            printf("pcre rc: %d\n", rc );
            switch(rc)
            {
                case PCRE_ERROR_NOMATCH:
                    printf("pcre: no match '%s' on pattern '%s'\n", path, n->combined_pattern);
                    break;

                // Handle other special cases if you like
                default:
                    printf("pcre matching error '%d' '%s' on pattern '%s'\n", rc, path, n->combined_pattern);
                    break;
            }
#endif
            return NULL;
        }


        for (i = 1; i < rc; i++)
        {
            substring_start = path + ov[2*i];
            substring_length = ov[2*i+1] - ov[2*i];
            // info("%2d: %.*s\n", i, substring_length, substring_start);

            if ( substring_length > 0) {
                restlen = path_len - ov[1]; // fully match to the end
                // info("matched item => restlen:%d edges:%d i:%d\n", restlen, n->edge_len, i);

                e = n->edges[i - 1];

                if (entry && e->has_slug) {
                    // append captured token to entry
                    str_array_append(entry->vars , zstrndup(substring_start, substring_length));
                }
                if (restlen == 0 ) {
                    return e->child && e->child->endpoint > 0 ? e->child : NULL;
                }
                // get the length of orginal string: $0
                return r3_tree_matchl( e->child, path + (ov[1] - ov[0]), restlen, entry);
            }
        }
        // does not match
        return NULL;
    }

    if ( (e = r3_node_find_edge_str(n, path, path_len)) != NULL ) {
        restlen = path_len - e->pattern_len;
        if (restlen == 0) {
            return e->child && e->child->endpoint > 0 ? e->child : NULL;
        }
        return r3_tree_matchl(e->child, path + e->pattern_len, restlen, entry);
    }
    return NULL;
}



route * r3_tree_match_route(const node *tree, match_entry * entry) {
    node *n;
    n = r3_tree_match_entry(tree, entry);
    if (n->routes && n->route_len > 0) {
        int i;
        for (i = 0; i < n->route_len ; i++ ) {
            if ( r3_route_cmp(n->routes[i], entry) == 0 ) {
                return n->routes[i];
            }
        }
    }
    return NULL;
}

inline edge * r3_node_find_edge_str(const node * n, char * str, int str_len) {
    unsigned short i = 0;
    char firstbyte = *str;
    for (; i < n->edge_len ; i++ ) {
        if ( firstbyte == *(n->edges[i]->pattern) ) {
            info("matching '%s' with '%s'\n", str, node_edge_pattern(n,i) );
            if ( strncmp( node_edge_pattern(n,i), str, node_edge_pattern_len(n,i) ) == 0 ) {
                return n->edges[i];
            }
            return NULL;
        }
    }
    return NULL;
}

node * r3_node_create() {
    node * n = (node*) zmalloc( sizeof(node) );
    n->edges = NULL;
    n->edge_len = 0;
    n->edge_cap = 0;

    n->routes = NULL;
    n->route_len = 0;
    n->route_cap = 0;

    n->endpoint = 0;
    n->combined_pattern = NULL;
    n->pcre_pattern = NULL;
    return n;
}


route * r3_route_create(char * path) {
    return r3_route_createl(path, strlen(path));
}

void r3_route_free(route * route) {
    zfree(route);
}

route * r3_route_createl(char * path, int path_len) {
    route * info = zmalloc(sizeof(route));
    info->path = path;
    info->path_len = path_len;
    info->request_method = 0; // can be (GET || POST)

    info->data = NULL;

    info->host = NULL; // required host name
    info->host_len = 0;

    info->remote_addr_pattern = NULL;
    info->remote_addr_pattern_len = 0;
    return info;
}

node * r3_tree_insert_pathl(node *tree, char *path, int path_len, void * data)
{
    return r3_tree_insert_pathl_(tree, path, path_len, NULL , data);
}


/**
 * Return the last inserted node.
 */
node * r3_tree_insert_pathl_(node *tree, char *path, int path_len, route * route, void * data)
{
    node * n = tree;
    edge * e = NULL;

    /* length of common prefix */
    int prefix_len = 0;
    for( int i = 0 ; i < n->edge_len ; i++ ) {
        prefix_len = strndiff(path, n->edges[i]->pattern, n->edges[i]->pattern_len);

        // printf("prefix_len: %d   %s vs %s\n", prefix_len, path, n->edges[i]->pattern );

        // no common, consider insert a new edge
        if ( prefix_len > 0 ) {
            e = n->edges[i];
            break;
        }
    }

    // branch the edge at correct position (avoid broken slugs)
    char *slug_s;
    if ( (slug_s = inside_slug(path, path_len, path + prefix_len)) != NULL ) {
        prefix_len = slug_s - path;
    }

    // common prefix not found, insert a new edge for this pattern
    if ( prefix_len == 0 ) {
        // there are two more slugs, we should break them into several parts
        int slug_cnt = slug_count(path, path_len);
        if ( slug_cnt > 1 ) {
            int   slug_len;
            char *p = slug_find_placeholder(path, &slug_len);

#ifdef DEBUG
            assert(p);
#endif

            // find the next one '{', then break there
            if(p) {
                p = slug_find_placeholder(p + slug_len + 1, NULL);
            }
#ifdef DEBUG
            assert(p);
#endif

            // insert the first one edge, and break at "p"
            node * child = r3_tree_create(3);
            r3_node_connect(n, zstrndup(path, (int)(p - path)), child);

            // and insert the rest part to the child
            return r3_tree_insert_pathl_(child, p, path_len - (int)(p - path),  route, data);

        } else {
            if (slug_cnt == 1) {
                // there is one slug, let's see if it's optimiz-able by opcode
                int   slug_len = 0;
                char *slug_p = slug_find_placeholder(path, &slug_len);
                int   slug_pattern_len = 0;
                char *slug_pattern = slug_find_pattern(slug_p, &slug_pattern_len);
                int opcode = 0;
                // if there is a pattern defined.
                if (slug_pattern) {
                    char *cpattern = slug_compile(slug_pattern, slug_pattern_len);
                    opcode = r3_pattern_to_opcode(cpattern, strlen(cpattern));
                    zfree(cpattern);
                } else {
                    opcode = OP_EXPECT_NOSLASH;
                }
                // found opcode
                if (opcode) {
                    // if the slug starts after one+ charactor, for example foo{slug}
                    node *c1;
                    if (slug_p > path) {
                        c1 = r3_tree_create(3);
                        r3_node_connectl(n, path, slug_p - path, 1, c1); // duplicate
                    } else {
                        c1 = n;
                    }

                    node * c2 = r3_tree_create(3);
                    edge * op_edge = r3_node_connectl(c1, slug_p, slug_len , 1, c2);
                    op_edge->opcode = opcode;

                    // insert rest
                    int restlen = (path_len - (slug_p - path)) - slug_len;
                    if (restlen) {
                        return r3_tree_insert_pathl_(c2, slug_p + slug_len, restlen, route, data);
                    }

                    c2->data = data;
                    c2->endpoint++;
                    if (route) {
                        route->data = data;
                        r3_node_append_route(c2, route);
                    }
                    return c2;
                }
            }
            // only one slug
            node * child = r3_tree_create(3);
            r3_node_connect(n, zstrndup(path, path_len) , child);
            child->data = data;
            child->endpoint++;
            if (route) {
                route->data = data;
                r3_node_append_route(child, route);
            }
            return child;
        }
    } else if ( prefix_len == e->pattern_len ) {    // fully-equal to the pattern of the edge

        char * subpath = path + prefix_len;
        int    subpath_len = path_len - prefix_len;

        // there are something more we can insert
        if ( subpath_len > 0 ) {
            return r3_tree_insert_pathl_(e->child, subpath, subpath_len, route, data);
        } else {
            // there are no more path to insert

            // see if there is an endpoint already
            if (e->child->endpoint > 0) {
                // XXX: return an error code instead of NULL
                return NULL;
            }
            e->child->endpoint++; // make it as an endpoint
            e->child->data = data;
            if (route) {
                route->data = data;
                r3_node_append_route(e->child, route);
            }
            return e->child;
        }

    } else if ( prefix_len < e->pattern_len ) {
        /* it's partially matched with the pattern,
         * we should split the end point and make a branch here...
         */
        char * s2 = path + prefix_len;
        int   s2_len = path_len - prefix_len;
        r3_edge_branch(e, prefix_len);
        return r3_tree_insert_pathl_(e->child, s2 , s2_len, route , data);
    } else {
        printf("unexpected route.");
        return NULL;
    }
    return n;
}

bool r3_node_has_slug_edges(node *n) {
    bool found = FALSE;
    edge *e;
    for ( int i = 0 ; i < n->edge_len ; i++ ) {
        e = n->edges[i];
        e->has_slug = contains_slug(e->pattern);
        if (e->has_slug)
            found = TRUE;
    }
    return found;
}



void r3_tree_dump(node * n, int level) {
    print_indent(level);

    printf("(o)");

    if ( n->combined_pattern ) {
        printf(" regexp:%s", n->combined_pattern);
    }

    printf(" endpoint:%d", n->endpoint);

    if (n->data) {
        printf(" data:%p", n->data);
    }
    printf("\n");

    for ( int i = 0 ; i < n->edge_len ; i++ ) {
        edge * e = n->edges[i];
        print_indent(level + 1);
        printf("|-\"%s\"", e->pattern);

        if (e->opcode ) {
            printf(" opcode:%d", e->opcode);
        }

        if ( e->child ) {
            printf("\n");
            r3_tree_dump( e->child, level + 1);
        }
        printf("\n");
    }
}


/**
 * return 0 == equal
 *
 * -1 == different route
 */
int r3_route_cmp(route *r1, match_entry *r2) {
    if (r1->request_method != 0) {
        if (0 == (r1->request_method & r2->request_method) ) {
            return -1;
        }
    }

    if ( r1->path && r2->path ) {
        if ( strcmp(r1->path, r2->path) != 0 ) {
            return -1;
        }
    }

    if ( r1->host && r2->host ) {
        if (strcmp(r1->host, r2->host) != 0 ) {
            return -1;
        }
    }

    if (r1->remote_addr_pattern) {
        /*
         * XXX: consider "netinet/in.h"
        if (r2->remote_addr) {
            inet_addr(r2->remote_addr);
        }
        */
        if ( strcmp(r1->remote_addr_pattern, r2->remote_addr) != 0 ) {
            return -1;
        }
    }
    return 0;
}


/**
 *
 */
void r3_node_append_route(node * n, route * r) {
    if (n->routes == NULL) {
        n->route_cap = 3;
        n->routes = zmalloc(sizeof(route) * n->route_cap);
    }
    if (n->route_len >= n->route_cap) {
        n->route_cap *= 2;
        n->routes = zrealloc(n->routes, sizeof(route) * n->route_cap);
    }
    n->routes[ n->route_len++ ] = r;
}