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

void parse_range(char *k, int *l1, int *l2) {
	*l1 = 0;
	*l2 = 0;
	while (k[0] == ' ' || k[0] == '\t') k++;

	while (k[0] >= '0' && k[0] <= '9') {
		(*l1) *= 10;
		(*l1) += (k[0] - '0');
		k++;
	}
	if (k[0] == '-') {
		k++;
		while (k[0] >= '0' && k[0] <= '9') {
			(*l2) *= 10;
			(*l2) += (k[0] - '0');
			k++;
		}
	}
	
	if (k[0] != 0) {
		*l1 = 0;
	}
	if (*l2 == 0) *l2 = *l1;

	if (*l1 == 0 || *l2 < *l1) {
		printf("Invalid range.");
		*l1 = 0;
	}
}

int main(int argc, char **args) {
	int linecount;
	char **lines;
	int i, j;

	readline_history hist;
	hist.str = 0; hist.max = 10;

	if (args[1] == 0) {
		printf("Usage: %s filename\n", args[0]);
	} else {
		// load file
		file_info info;
		int e = stat(args[1], &info);
		if (e == E_NOT_FOUND) {
			printf("File not found. Creating new file.\n");
			linecount = 0;
			lines = malloc(1 * sizeof(char*));
			lines[0] = 0;
		} else if (info.type & FT_FILE) {
			int f = open(args[1], FM_READ);
			char* buff = (char*)malloc(info.size);
			read(f, 0, info.size, buff);
			close(f);

			// count newlines
			linecount = 1;
			for (i = 0; i < info.size; i++) {
				if (buff[i] == '\n') linecount++;
			}
			lines = malloc(linecount * sizeof(char*));

			// copy lines
			i = 0;
			int p = 0, l = 0;
			while (i <= info.size) {
				if ((i == info.size && buff[i-1] != 0) || buff[i] == '\n') {
					lines[l] = malloc(i - p + 1);
					for (j = 0; j < i-p; j++) lines[l][j] = buff[p+j];
					lines[l][i-p] = 0;
					l++;
					p = i+1;
				}
				i++;
			}
			while (l < linecount) linecount--;

			if (linecount > 0 && lines[linecount-1][0] == 0) {
				free(lines[linecount-1]);
				linecount--;
			}

			// free buffer
			free(buff);
		} else {
			printf("%s is not a file. Exiting.\n", args[1]);
			return -1;
		}

		// run
		while (lines) {
			printf("[%d lines] ", linecount);
			char *s = freadline(stdin, &hist);
			if (strcmp(s, "q") == 0) {
				break;
			} else if (strcmp(s, "l") == 0) {
				for (i = 0; i < linecount; i++) {
					printf("%d\t%s\n", i + 1, lines[i]);
				}
			} else if (s[0] == 'l') {
				int l1, l2;
				parse_range(s + 1, &l1, &l2);
				if (l1 != 0) {
					if (l2 > linecount) {
						printf("There are only %d lines.\n", linecount);
					} else {
						for (i = l1; i <= l2; i++) {
							printf("%d\t%s\n", i, lines[i-1]);
						}
					}
				}
			} else if (strcmp(s, "w") == 0) {
				// calculate buffer size
				int buffsz = 0;
				for (i = 0; i < linecount; i++) {
					buffsz += strlen(lines[i]) + 1;
				}

				//write buffer
				char *buff = malloc(buffsz);
				char *p = buff;
				for (i = 0; i < linecount; i++) {
					for (j = 0; lines[i][j]; j++) {
						*(p++) = lines[i][j];
					}
					*(p++) = '\n';
				}

				// write buffer
				int f = open(args[1], FM_WRITE | FM_TRUNC | FM_CREATE | FT_FILE);
				if (f > 0) {
					write(f, 0, buffsz, buff);
					close(f);
					printf("%s written, %d lines, %d characters\n", args[1], linecount, buffsz);
				} else {
					printf("Error %d in opening %s\n", f, args[1]);
				}
				free(buff);
			} else if (s[0] >= '1' && s[0] <= '9') {
				int line = 0;
				i = 0;
				while (s[i] >= '0' && s[i] <= '9') {
					line *= 10;
					line += (s[i] - '0');
					i++;
				}
				if(s[i] == ' ' || s[i] == '\t') i++;
				char *nl = s + i;
				
				if (line < 1) {
					printf("Invalid line number.\n");
					continue;
				}

				if (line > linecount) {
					char **lines2 = malloc(line * sizeof(char*));
					for (i = 0; i < linecount; i++) {
						lines2[i] = lines[i];
					}
					for (i = linecount; i < line; i++) {
						lines2[i] = strdup("");
					}
					free(lines); //PB
					lines = lines2;
					linecount = line;
				}

				free(lines[line-1]);
				lines[line-1] = strdup(nl);
			} else if (s[0] == 'd') {
				int l1, l2;
				parse_range(s + 1, &l1, &l2);
				if (l1 != 0) {
					l1--;
					for (i = l1; i < l2; i++) {
						free(lines[i]);
					}
					for (i = l2; i < linecount; i++) {
						lines[i - (l2 - l1)] = lines[i];
					}
					linecount -= (l2 - l1);
				}
			} else {
				printf("Unknown command: %s\n", s);
			}
		}
	}

	return 0;
}