/*
 * Created by gmgauthier on 05/10/2025.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "platform.h"
#include "config.h"

#define MAX_LENGTH 500 /* Allow fgets to read up to this many characters */
#define DATE_LENGTH 10 /* YYYY-MM-DD */
#define TIME_LENGTH 5 /* HH:MM */
#define TXTMSG_LENGTH 125 /* Max length of a text message */


typedef enum {
    SORT_NONE,
    SORT_DATE,
    SORT_CATEGORY
} SortMode;

/* Global variable to control sort order: 1 for ascending, -1 for descending */
static int g_sort_order = -1; /* Default: descending (newest/Z-A first) */


typedef struct {
    char date[DATE_LENGTH +1]; /* YYYY-MM-DD\0 */
    char time[TIME_LENGTH +1]; /* HH:MM\0 */
    char category[CATEGORY_LENGTH +1]; /* CATEGORY__\0 */
    char text[TXTMSG_LENGTH +1]; /* Text message\0 */
} Entry;

/* Comparison function for sorting by date/time */
static int compare_by_date(const void *a, const void *b) {
    const Entry *entry_a = (const Entry *)a;
    const Entry *entry_b = (const Entry *)b;
    int date_cmp = strcmp(entry_a->date, entry_b->date);
    if (date_cmp != 0) return date_cmp * g_sort_order;
    return strcmp(entry_a->time, entry_b->time) * g_sort_order;
}

/* Comparison function for sorting by category */
static int compare_by_category(const void *a, const void *b) {
    const Entry *entry_a = (const Entry *)a;
    const Entry *entry_b = (const Entry *)b;
    return strcmp(entry_b->category, entry_a->category) * g_sort_order;
}

void print_horizontal_line(char left, char middle, char right, char fill) {
    int i;
    printf("%c", left);

    /* Date column */
    for (i = 0; i < DATE_LENGTH + 2; i++) printf("%c", fill);
    printf("%c", middle);

    /* Time column */
    for (i = 0; i < TIME_LENGTH + 2; i++) printf("%c", fill);
    printf("%c", middle);

    /* Category column */
    for (i = 0; i < CATEGORY_LENGTH + 2; i++) printf("%c", fill);
    printf("%c", middle);

    /* Free text column */
    for (i = 0; i < TXTMSG_LENGTH + 2; i++) printf("%c", fill);
    printf("%c\n", right);
}

void print_header(void) {
    /* Top border (double line) */
    print_horizontal_line('+', '+', '+', '=');

    /* Header row */
    printf("| %-*s | %-*s | %-*s | %-*s |\n",
           DATE_LENGTH, "Date",
           TIME_LENGTH, "Time",
           CATEGORY_LENGTH, "Category",
           TXTMSG_LENGTH, "Free Text");

    /* Bottom border (double line) */
    print_horizontal_line('+', '+', '+', '=');
}

void print_footer(void) {
    print_horizontal_line('+', '+', '+', '-');
}

void print_entry(const Entry *entry) {
    printf("| %-*s | %-*s | %-*s | %-*s |\n",
           DATE_LENGTH, entry->date,
           TIME_LENGTH, entry->time,
           CATEGORY_LENGTH, entry->category,
           TXTMSG_LENGTH, entry->text);
}


/* Parse a fixed-length field followed by a delimiter */
static const char *parse_fixed_field(const char *ptr, char *dest, int length, char delimiter) {
    if ((int)strlen(ptr) < length) return NULL;
    strncpy(dest, ptr, length);
    dest[length] = '\0';
    ptr += length;
    if (*ptr != delimiter) return NULL;
    return ptr + 1; /* skip delimiter */
}

/* Parse a variable-length field up to max_length, terminated by delimiter */
/* Truncates if field exceeds max_length but continues to find delimiter */
static const char *parse_variable_field(const char *ptr, char *dest, int max_length, char delimiter) {
    int i = 0;
    while (*ptr != '\0' && *ptr != delimiter) {
        if (i < max_length) {
            dest[i++] = *ptr;
        }
        ptr++;
    }
    dest[i] = '\0';
    if (*ptr != delimiter) return NULL;
    return ptr + 1; /* skip delimiter */
}

int parse_line(const char *line, Entry *entry) {
    const char *charptr = line;

    /* Parse date field (fixed length) */
    charptr = parse_fixed_field(charptr, entry->date, DATE_LENGTH, ',');
    if (!charptr) return 0;

    /* Parse time field (fixed length) */
    charptr = parse_fixed_field(charptr, entry->time, TIME_LENGTH, ',');
    if (!charptr) return 0;

    /* Parse category field (variable length) */
    charptr = parse_variable_field(charptr, entry->category, CATEGORY_LENGTH, ',');
    if (!charptr) return 0;

    /* Parse text field (variable length, quoted) */
    if (*charptr != '"') return 0;
    charptr++;
    charptr = parse_variable_field(charptr, entry->text, TXTMSG_LENGTH, '"');
    if (!charptr) return 0;

    return 1;
}

int get_cnotes_path(char *buffer, size_t bufsize) {
    const char *custom_path;
    const char *home;
    size_t len;

    /* First check for CNOTES_PATH environment variable override */
    custom_path = getenv(CNOTES_PATH_ENV);
    if (custom_path != NULL && strlen(custom_path) > 0) {
        if (strlen(custom_path) + strlen(CNOTES_FILE) + 2 > bufsize) {
            fprintf(stderr, "Error: Path too long\n");
            return 0;
        }
        sprintf(buffer, "%s" PATH_SEP_STR "%s", custom_path, CNOTES_FILE);
        return 1;
    }

    /* Fall back to HOME_ENV + CNOTES_DIR */
    home = getenv(HOME_ENV);
    if (home == NULL) {
        fprintf(stderr, "Error: %s environment variable not set\n", HOME_ENV);
        fprintf(stderr, "Hint: Set %s to specify notes directory\n", CNOTES_PATH_ENV);
        return 0;
    }

    /* Build path to cnotes file */
    len = strlen(home);
    if (strlen(CNOTES_DIR) == 0) {
        /* DOS mode: file in home directory directly */
        if (len + strlen(CNOTES_FILE) + 2 > bufsize) {
            fprintf(stderr, "Error: Path too long\n");
            return 0;
        }
        sprintf(buffer, "%s" PATH_SEP_STR "%s", home, CNOTES_FILE);
    } else {
        /* Unix/Windows: HOME/CNOTES_DIR/CNOTES_FILE */
        if (len + strlen(CNOTES_DIR) + strlen(CNOTES_FILE) + 3 > bufsize) {
            fprintf(stderr, "Error: Path too long\n");
            return 0;
        }
        sprintf(buffer, "%s" PATH_SEP_STR "%s" PATH_SEP_STR "%s", home, CNOTES_DIR, CNOTES_FILE);
    }
    return 1;
}

/* start with a simple cat of the file */
int main(int argc, char *argv[]) {
    int i;
    FILE *notesfile;
    char file_path[600];
    Entry *entries;
    int entry_count = 0;
    char line[MAX_LENGTH +1];
    char *filename = NULL;
    SortMode sort_mode = SORT_NONE;

    /* Insures that we won't run out of memory in DOS */
    entries = (Entry *)malloc(MAX_ENTRIES * sizeof(Entry));
    if (entries == NULL) {
        fprintf(stderr, "Error: Cannot allocate memory\n");
        return 1;
    }

    /* Parse command line arguments */
    for (i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-d") == 0 || strcmp(argv[i], "--date") == 0) {
            if (sort_mode != SORT_NONE) {
                fprintf(stderr, "cndump: cannot specify multiple sort options\n");
                fprintf(stderr, "usage: cndump [[-d|--date] | [-c|--category]] [-r|--reverse] [filename]\n");
                exit(1);
            }
            sort_mode = SORT_DATE;
        }

        else if (strcmp(argv[i], "-c") == 0 || strcmp(argv[i], "--category") == 0) {
            if (sort_mode != SORT_NONE) {
                fprintf(stderr, "cndump: cannot specify multiple sort options\n");
                fprintf(stderr, "usage: cndump [[-d|--date] | [-c|--category]] [-r|--reverse] [filename]\n");
                exit(1);
            }
            sort_mode = SORT_CATEGORY;
        }

        else if (strcmp(argv[i], "-r") == 0 || strcmp(argv[i], "--reverse") == 0) {
            g_sort_order = 1; /* Ascending order */
        }

        else {
            filename = argv[i];
        }
    }

    /* TODO: filename argument is parsed but not yet used */
    (void)filename;

    /* Get cnotes file path */
    if (!get_cnotes_path(file_path, sizeof(file_path))) {
        return 1;
    }

    notesfile = fopen(file_path, "r");
    if (notesfile == NULL) {
        fprintf(stderr, "Error: Cannot open file '%s'\n", file_path);
        fprintf(stderr, "Hint: Use 'cnadd' to create your first entry\n");
        return 1;
    }

    /* Read all entries into memory */
    while (fgets(line, MAX_LENGTH, notesfile) != NULL && entry_count < MAX_ENTRIES) {
        if (parse_line(line, &entries[entry_count])) {
            entry_count++;
        }
        else {
            fprintf(stderr, "cndump: invalid line: %s\n", line);
        }
    }
    fclose(notesfile);

    /* Sort if requested */
    if (sort_mode == SORT_DATE) {
        qsort(entries, entry_count, sizeof(Entry), compare_by_date);
    }
    else if (sort_mode == SORT_CATEGORY) {
        qsort(entries, entry_count, sizeof(Entry), compare_by_category);
    }

    /* Print the table */
    print_header();
    for (i = 0; i < entry_count; i++) {
        print_entry(&entries[i]);
    }
    print_footer();

    free(entries);
    return 0;
}