/// dynamic array class
/// written by: Harry Irving

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

typedef enum LineState {
    UNMODIFIED,
    MODIFIED,
    ADDED,
    REMOVED,
} LineState;

typedef struct {
    uint32_t size;      // Current number of elements
    uint32_t capacity;  // Total capacity allocated
    LineState* data;    // Array of LineState values
} StateArray;

StateArray arr_init(int capacity) {
    // creates a new array to store the state
    StateArray arr;
    arr.size = capacity;
    arr.capacity = capacity;
    arr.data = (LineState*)calloc(capacity, sizeof(LineState));
    // Initialize all elements to UNMODIFIED
    for (int i = 0; i < capacity; i++) {
        arr.data[i] = UNMODIFIED;
    }
    return arr;
}

// prints the state of the array into a file
// this method is for debug purposes!
// void arr_print(StateArray* self) {
//     FILE* log_file = fopen("diff.txt", "w");
//     if (log_file == NULL) {
//         fprintf(stderr, "Error: Could not open log file\n");
//     }

//     for (int i = 0; i < self->size; i++) {
//         switch (self->data[i]) {
//             case UNMODIFIED:
//                 fwrite("UNMODIFIED\n", sizeof(char), strlen("UNMODIFIED\n"), log_file);
//                 break;
//             case MODIFIED:
//                 fwrite("MODIFIED\n", sizeof(char), strlen("MODIFIED\n"), log_file);
//                 break;
//             case ADDED:
//                 fwrite("ADDED\n", sizeof(char), strlen("ADDED\n"), log_file);
//                 break;
//             case REMOVED:
//                 fwrite("REMOVED\n", sizeof(char), strlen("REMOVED\n"), log_file);
//                 break;
//         }
//     }

//     fclose(log_file);
// }

// calculates an offset to use for indexing into the state relative to the buffer.
// this is because some elements might not be aligned due to needing to insert the "REMOVED" element in some cases.
int arr_added_or_removed_before(StateArray* self, int index) {
    int count = 0;
    for (int i = 0; i < index; i++) {
        // if (self->data[i] == ADDED || self->data[i] == REMOVED) {
        //     if (self->data[i] == REMOVED) {
        //         // every time a "REMOVED" element is found, we increase the index by 1
        //         index++;
        //     }
        //     count++;
        // }
        if (self->data[i] == REMOVED) {
            // every time a "REMOVED" element is found, we increase the index by 1
            index++;
            count++;
        }
    }
    return count;
}

void arr_set(StateArray* self, int index, LineState state) {
    int offset = arr_added_or_removed_before(self, index);
    self->data[index] = state;
}

LineState arr_remove(StateArray* self, int index) {
    int offset = arr_added_or_removed_before(self, index);

    if (index >= self->size) {
        return -1;
    }

    LineState removed = self->data[index];
    
    // Shift remaining elements left
    for (int i = index; i < self->size - 1; i++) {
        self->data[i] = self->data[i + 1];
    }
    self->size--;
    
    return removed;
}

int arr_insert(StateArray* self, int index, LineState state) {
    int offset = arr_added_or_removed_before(self, index);

    if (index > self->size) {
        return -1;
    }
    self->size++;

    // Grow array if needed
    if (self->size > self->capacity) {
        self->capacity = (self->size) * sizeof(LineState);
        self->data = (LineState*)realloc(self->data, self->capacity * sizeof(LineState));
    }

    // Shift elements right to make room
    for (int i = self->size - 1; i > index; i--) {
        self->data[i] = self->data[i - 1];
    }
    self->data[index] = state;
    return 0;
}

LineState arr_get(StateArray* self, int index) {
    int offset = arr_added_or_removed_before(self, index);
    return self->data[index];
}

int arr_original_offset(StateArray* self, int index) {
    int offset = 0;
    for (int i = 0; i < index; i++) {
        if (self->data[i] == ADDED) {
            offset--;
        }
    }
    return offset;
}

int arr_modified_offset(StateArray* self, int index) {
    int offset = 0;
    for (int i = 0; i < index; i++) {
        if (self->data[i] == REMOVED) {
            offset--;
        }
    }
    return offset;
}

int arr_dealloc(StateArray* self) {
    free(self->data);
    self->data = NULL;
    self->size = 0;
    self->capacity = 0;
    return 0;
}