#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#include "read.h"
#include "strbst.h"
#include "nodelink.h"
#include "ll.h"

static void consumespaces(FILE* file) {
    // used to consume spaces in an item ("-  list item" -> "list item")
    int c;
    while ( ( c = fgetc(file) ) != EOF && c == ' ' );
    ungetc(c, file);
}

static void wsclean(char* txt, size_t* sz){
    // "string\n  \n" -> "string\n" (must always end with \n)
    for (; *sz > 0; (*sz)--) { // start at end [i-1] and dec
        if (txt[*sz-1] != ' ' && txt[*sz-1] != '\n') break;
    }
    txt[*sz] = '\n'; txt[*sz+1] = 0;// finish string
}

static char* empty(void) {
    // "" with a freeable memory address
    char* str = malloc(sizeof(char));
    *str = 0;
    return str;
}

static char* getline(size_t* n, FILE* file) {
    // Can probably be improved by using posix file apis
    size_t sz = 100;
    *n = 0;
    int c;
    char* out = malloc(sizeof(char)*sz);
    while ( (c = fgetc(file)) != EOF ) {
        if (*n == sz-1) out = realloc(out, sizeof(char) * (sz *= 2));
        out[*n] = c;
        (*n)++;
        if (c == '\n') break;
    }
    out[*n] = 0;
    return realloc(out, sizeof(char) * (*n+1) );
}

static char* line(FILE* file, bool nl) { // gets a line from file
    size_t n;
    char* link = getline(&n, file);
        // getline stores a line of len n (size n+1) in link
    wsclean(link, &n); // removes trailing whitespace
    if (n == 0) { // "\n" => ""
        free(link);
        return empty();
    } else { // else return obtained
        if (!nl) link[n] = 0; //truncate the newline
        return link;
    }
}

static link* insorget(strbst* tgt, char* name, bool tofree) {
    link* get = query(tgt, name);
    if (!get) {
        get = newlink(newnode());
        insbst(tgt, name, get);
    } else if (tofree) {
        free(name);
    }
    return get;
}

static link* addbstlink(strbst* tree, char* name, node* to, bool f) {
    link* l = query(tree, name);
    if (l && f) {
        free(name);
        return l;
    }
    l = newlink(to);
    insbst(tree, name, l);
    return l;
}

static char* resolvell(llnode* tail, size_t sz) {
    char *out, *pos;
    pos = out = malloc(sizeof(char)*(sz+1)); out[sz] = 0;
    while (tail != NULL) {
        size_t len = strlen(tail->str);
        memcpy(pos, tail->str, len);
        pos += len;
        llnode* tmp = tail;
        tail = tail->next;
        free(tmp->str); free(tmp);
    }
    return out;
}

static void stradd(char** orig, char* new) { // new is freed
    size_t nsz = strlen(new)+1;
    size_t olen = strlen(*orig);
    *orig = realloc(*orig,olen+nsz);
    memcpy(*orig+olen,new,nsz);
    free(new);
}

node* readfile(char* name) {
    FILE* read = fopen(name, "r");
    node *root, *cur;
    cur = root = newnode();
    link* curl = addbstlink(root->links, "", root, false);

    llnode start;
    start.next = NULL; // empty desc isn't undefined
    llnode *head, *tail;
    head = tail = &start;
    size_t sz = 0;

    int c;
    while ( ( c = fgetc(read) ) != EOF ) {
        if (c == ':' || c == '-') {
            stradd(&(curl->desc),resolvell(head->next, sz));
            head->next = NULL;
            tail = head;
            sz = 0;
            consumespaces(read);
        }
        switch (c) {
            case ':':
                curl = insorget(root->links, line(read, false), true);
                cur = curl->to;
                break;

            case '-': ; // ': ;' (empty expr) needed before 'char*'
                char* lname = line(read, false);
                node* at = insorget(root->links, lname, false)->to;
                curl = addbstlink(cur->links, lname, at, true);
                break;

            case '!': ;
                char* l = line(read,false);
                FILE* f = fopen(l,"r");
                if (!f) {
                    printf("Failed to open %s\n",l);
                    break;
                }
                char* ln; size_t n;
                while ( *(ln = getline(&n,f)) ) {
                    if (*ln=='\n'){
                        free(ln);
                        ln = empty();
                        sz -= n;
                    }
                    tail = appendll(tail, ln);
                    sz += n;
                }
                fclose(f);
                break;

            default:
                ungetc(c, read);
            case '.':
                tail = appendll(tail, line(read, true));
                // TODO: appendll should change strlen, and
                // line() needs to return a size
                sz += strlen(tail->str);
                break;
        }
    }
    stradd(&(curl->desc),resolvell(head->next, sz));
    fclose(read);
    return root;
}