#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "evil.h"

static char *txtfile = NULL;

void printOp(operator_t op) {
        switch(op) {
                case(ADD):
                        printf("+");
                        break;
                case(SUB):
                        printf("-");
                        break;
                case(MUL):
                        printf("*");
                        break;
                case(DIV):
                        printf("/");
                        break;
                case(PAL):
                        printf("pal");
                        break;
                default:
                        printf("???");
        }
}

bool printEvil(uint32_t number) {
        /* We open the file for each iteration, but there's ~2 iterations, so it's fine */
        FILE *file = NULL;
        if (NULL != txtfile) {
                file = fopen(txtfile, "r");
        } else {
                file = fopen("evil.txt", "r");
        }
        if (NULL == file) {
                perror("Error opening txt file");
                return false;
        }
        char line[1024];
        while (fgets(line, sizeof(line), file)) {
                if (atoi(line) == number) {
                        char *reason = strchr(line, ' ');
                        if (0 == reason) {
                                printf("an illegal number: malformed txt file!\n");
                                return false;
                        }
                        /* Remove the newline at the end, Windows users are in for a surprise */
                        reason[strlen(reason)-1] = '\0';
                        /* Remove the space at the beginning */
                        printf("%s", reason+1);
                        break;
                }
        }
        fclose(file);
        return true;
}

/* Decode an entry in evilDb */
void decodeEntry(uint32_t value, uint64_t *db) {
        uint64_t entry = db[value];
        uint32_t parent = (uint32_t) (entry >> 32);
        operator_t operator = (operator_t) ((entry >> INDEXBITS) & 7);
        uint32_t ref = entry & INDEXMASK;
        if (0 == operator) {
                printf("%d is not in the database\n", value);
        } else if (PAL == operator) {
                printf("%d is %d reversed\n", value, parent);
        } else if (0 != parent) {
                printf("%d = %d ", value, parent);
                printOp(operator);
                printf(" %d (", ref);
                if (!(printEvil(ref))) {
                        free(db);
                        exit(42);
                }
                printf(")\n");
        } else {
                printf("%d is ", ref);
                if (!(printEvil(ref))) {
                        free(db);
                        exit(42);
                }
                printf(".\n");
        }
}

/* Print proof of evilness for value */
void find(uint32_t value, uint64_t *db) {
        while (0 != value) {
                decodeEntry(value, db);
                uint64_t entry = db[value];
                value = (uint32_t) (entry >> 32);
        }
}

int main(int argc, char *argv[]) {
        char *dbfile = NULL;
        uint64_t *db = NULL;
        int number = 0;
        bool first = true;
        for (int i = 1; i<argc; i++) {
                int len = strlen(argv[i]);
                if ((len > 4) && (strcmp(argv[i] + len - 4, ".txt") == 0)) {
                        txtfile = argv[i];
                        printf("Using %s for reference.\n", txtfile);
                } else if ((len > 3) && (strcmp(argv[i] + len - 3, ".db") == 0)) {
                        dbfile = argv[i];
                        printf("Using %s as database.\n", dbfile);
                } else {
                        // Attempt to convert string to number
                        bool isNumber = true;
                        for (int j=0; j<len; j++) {
                                printf("  %c  ", argv[i][j]);
                                if (!isdigit(argv[i][j])) {
                                        isNumber = false;
                                }
                        }
                        printf("\n");
                        if (isNumber) {
                                int literal = atoi(argv[i]);
                                number += literal;
                                if (first) {
                                        printf("  %d = %d\n", literal, number);
                                        first = false;
                                } else {
                                        printf("+ %d = %d\n", literal, number);
                                }
                        } else {
                                for (int j=0; j<len; j++) {
                                        char ord = (char) argv[i][j];
                                        int digit = 0;
                                        if ('0' > ord) {
                                                // pass
                                        } else if ('9' >= ord) {
                                                digit = ord - '0';
                                        } else if ('A' > ord) {
                                                // pass
                                        } else if ('Z' >= ord) {
                                                digit = ord - 'A' + 1;
                                        } else if ('a' > ord) {
                                                // pass
                                        } else if ('z' >= ord) {
                                                digit = ord - 'a' + 1;
                                        }
                                        number += digit;
                                        if (first) {
                                                printf("  %02d ", digit);
                                                first = false;
                                        } else {
                                                printf("+ %02d ", digit);
                                        }
                                }
                                printf(" = %d\n", number);
                        }
                        printf("\n");
                }
        }
        if (0 == number) {
                printf("Usage: %s 668\n", argv[0]);
                exit(0);
        }

        // Load database
        FILE *fp = NULL;
        if(NULL != dbfile) {
                fp = fopen(dbfile, "rb");
        } else {
                fp = fopen("evil.db", "rb");
        }
        if (NULL == fp) {
                perror("fopen");
                exit(1);
        }
        fseek(fp, 0, SEEK_END);
        int size = ftell(fp);
        fseek(fp, 0, SEEK_SET);
        if (0 != (size & 0x3)) {
                fclose(fp);
                printf("Database malformed\n");
                exit(10);
        }
        if ((number > size) || number < 0) {
                printf("%d is not in the database!\n", number);
        } else {
                db = (uint64_t*) malloc(size);
                size /= sizeof(uint64_t);
                size_t read = fread(db, sizeof(uint64_t), size, fp);
                fclose(fp);
                if (size != read) {
                        printf("Database size was %d, expected %d\n", (int) read, size);
                        perror("fread");
                        free(db);
                        exit(2);
                }
                find(number, db);
                free(db);
        }

        printf("Coincidence? I think not!\n");
        exit(0);
}