// Assignment 2 20T1 COMP1511: CS bEats
// beats.c
//
// The purpose of this program is to categorise music input.
//
// Version 1.0.0: Assignment released.
// Version 1.0.1: Fix default return value of add_musical_note_to_beat.

#include <assert.h>
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

#include "beats.h"

struct track {
    struct beat *head;
    struct beat *cur;
};

struct beat {
    struct note *notes;
    struct beat *next;
};

struct note {
    int oct;
    int key;
    struct note *next;
};

////////////////////////////////////////////////////////////////////////
//                       User Defined Functions                       //
////////////////////////////////////////////////////////////////////////

// Returns a value representing the pitch.
static int get_pitch(const int octave, const int key) {
    return (octave * 12) + (key);
}

// Return a malloced beat with fields initialised.
struct beat *create_beat() {
    Beat new_beat = malloc(sizeof(struct beat));
    assert(new_beat != NULL);

    new_beat->next = NULL;
    new_beat->notes = NULL;

    return new_beat;
}

// Returns the tail of a note linked list.
static struct note *get_note_tail(struct note *nhead) {
    if (nhead == NULL) {
        return NULL;
    }
    struct note *ret = nhead;
    while (ret->next != NULL) {
        ret = ret->next;
    }
    return ret;
}

// Returns the tail of a beat linked list.
static struct beat *get_beat_tail(struct beat *bhead) {
    if (bhead == NULL) {
        return NULL;
    }
    struct beat *ret = bhead;
    while (ret->next != NULL) {
        ret = ret->next;
    }
    return ret;
}

// Returns a malloced Note with fields initialised.
static struct note *create_note() {
    struct note *ret = malloc(sizeof(struct note));
    assert(ret != NULL);

    ret->oct = 0;
    ret->key = 0;
    ret->next = NULL;
    return ret;
}

// Inserts a note into a linked list of notes before the target note.
static void insert_note_before(struct beat *beat, struct note *note,
                        struct note *target) {
    if (beat->notes == target) {
        beat->notes = note;
        note->next = target;
        return;
    }
    for (struct note *i = beat->notes; i != NULL; i = i->next) {
        if (i->next == target) {
            i->next = note;
            note->next = target;
            return;
        }
    }
}

////////////////////////////////////////////////////////////////////////
//                         Stage 1 Functions                          //
////////////////////////////////////////////////////////////////////////

// Add a note to the end of a beat.
int add_note_to_beat(struct beat *const beat, const int oct, const int key) {
    if (oct < 0 || oct >= 10) {
        return INVALID_OCTAVE;
    }
    if (key < 0 || key >= 12) {
        return INVALID_KEY;
    }

    struct note *ntail = get_note_tail(beat->notes);
    if (ntail != NULL) {
        if (get_pitch(oct, key) <= get_pitch(ntail->oct, ntail->key)) {
            return NOT_HIGHEST_NOTE;
        }
    }
    struct note *new_note = create_note();
    new_note->oct = oct;
    new_note->key = key;
    new_note->next = NULL;

    if (ntail == NULL) {
        beat->notes = new_note;
    } else {
        ntail->next = new_note;
    }
    return VALID_NOTE;
}

// Print the contents of a beat.
void print_beat(struct beat *const beat) {
    if (beat == NULL) {
        return;
    }
    if (beat->notes == NULL) {
        printf("\n");
        return;
    }
    for (struct note *i = beat->notes; i != NULL; i = i->next) {
        printf("%d ", i->oct);
        if (i->key >= 10) {
            printf("%d", i->key % 12);
        } else {
            printf("%d%d", i->key / 12, i->key % 12);
        }
        if (i->next) {
            printf(" | ");
        }
    }
    printf("\n");
}

// Count the number of notes in a beat that are in a given octave.
int count_notes_in_octave(struct beat *const beat, int oct) {
    if (beat->notes == NULL) {
        return 0;
    }
    int notes = 0;
    for (struct note *i = beat->notes; i != NULL; i = i->next) {
        if (i->oct == oct) {
            ++notes;
        }
    }
    return notes;
}

////////////////////////////////////////////////////////////////////////
//                         Stage 2 Functions                          //
////////////////////////////////////////////////////////////////////////

// Return a malloced track with fields initialized.
struct track *create_track(void) {
    struct track *ret = malloc(sizeof(struct track));
    ret->head = NULL;
    ret->cur = NULL;
    return ret;
}

// Add a beat after the current beat in a track.
void add_beat_to_track(struct track *track, struct beat *beat) {
    if (track->cur != NULL) { // this behaviour may be unwanted
        if (track->cur->next != NULL) {
            beat->next = track->cur->next;
            track->cur->next = beat;
        } else {
            track->cur->next = beat;
        }
    } else {
        if (track->head == NULL) {
            track->head = beat;
        } else {
            beat->next = track->head;
            track->head = beat;
        }
    }
}

// Set a track's current beat to the next beat.
int select_next_beat(struct track *track) {
    if (track->cur == NULL) {
        if (track->head == NULL) {
            return TRACK_STOPPED;
        } else {
            track->cur = track->head;
            return TRACK_PLAYING;
        }
    } else {
        if (track->cur->next == NULL) {
            track->cur = NULL;
            return TRACK_STOPPED;
        } else {
            track->cur = track->cur->next;
            return TRACK_PLAYING;
        }
    }
}

// Print the contents of a track.
void print_track(struct track *track) {
    if (track->head == NULL) {
        return;
    }
    int count = 1;
    for (struct beat *i = track->head; i != NULL; i = i->next) {
        if (i == track->cur) {
            printf(">");
        } else {
            printf(" ");
        }
        printf("[%d] ", count);
        print_beat(i);
        ++count;
    }
}

// Count beats after the current beat in a track.
int count_beats_left_in_track(struct track *track) {
    int count = 0;
    if (track == NULL || track->head == NULL) {
        return count;
    }
    struct beat *i = track->cur;
    if (i == NULL) {
        i = track->head;
    }
    for (; i != NULL; i = i->next) {
        ++count;
    }
    if (track->cur) {
        --count;
    }
    return count;
}

////////////////////////////////////////////////////////////////////////
//                         Stage 3 Functions                          //
////////////////////////////////////////////////////////////////////////

// Free the memory of a beat, and any memory it points to.
void free_beat(struct beat *beat) {
    if (beat == NULL) {
        return;
    }
    if (beat->notes != NULL) {
        struct note *i = beat->notes;
        struct note *forwards = i->next;
        while (i != NULL) {
            forwards = i->next;
            free(i);
            i = forwards;
        }
    }
    free(beat);
}

// Free the memory of a track, and any memory it points to.
void free_track(struct track *track) {
    if (track == NULL) {
        return;
    }
    if (track->head != NULL) {
        struct beat *i = track->head;
        struct beat *forwards = i->next;
        while (i != NULL) {
            forwards = i->next;
            free_beat(i);
            i = forwards;
        }
    }
    free(track);
}

// Remove the currently selected beat from a track.
int remove_selected_beat(struct track *track) {
    if (track->cur == NULL) {
        return TRACK_STOPPED;
    }
    struct beat *backwards = NULL;
    struct beat *forwards = NULL;
    for (struct beat *i = track->head; i != NULL; i = i->next) {
        if (i == track->cur) {
            track->head = i->next;
            forwards = i->next;
            free_beat(track->cur);
            break;
        } else if (i->next == track->cur) {
            backwards = i;
            forwards = i->next->next;
            free_beat(track->cur);
            backwards->next = forwards;
            break;
        }
    }
    if (forwards == NULL) {
        track->cur = NULL;
        return TRACK_STOPPED;
    } else {
        track->cur = forwards;
        return TRACK_PLAYING;
    }
}

////////////////////////////////////////////////////////////////////////
//                         Stage 4 Functions                          //
////////////////////////////////////////////////////////////////////////

// Add note to beat, given its 'musical notation'.
int add_musical_note_to_beat(Beat beat, char *string) {
    int oct = string[0] - '0';
    if (oct < 0 || oct > 9) {
        return INVALID_MUSICAL_NOTE;
    }
    int key = 0;
    switch (string[1]) {
    case 'A':
        key = 0;
        break;
    case 'B':
        key = 2;
        break;
    case 'C':
        key = 3;
        break;
    case 'D':
        key = 5;
        break;
    case 'E':
        key = 7;
        break;
    case 'F':
        key = 8;
        break;
    case 'G':
        key = 10;
        break;
    default:
        return INVALID_MUSICAL_NOTE;
    }
    for (char *c = string + 2; *c != '\0'; ++c) {
        if (*c == '#') {
            ++key;
        } else {
            return INVALID_MUSICAL_NOTE;
        }
    }
    int pitch = get_pitch(oct, key);
    oct = pitch / 12;
    key = pitch % 12;
    struct note *tail = get_note_tail(beat->notes);
    if (tail == NULL || get_pitch(tail->oct, tail->key) < pitch) {
        add_note_to_beat(beat, oct, key);
        return VALID_NOTE;
    }
    struct note *higher = NULL;
    for (struct note *i = beat->notes; i != NULL; i = i->next) {
        int iter_pitch = get_pitch(i->oct, i->key);
        if (iter_pitch == pitch) {
            return INVALID_MUSICAL_NOTE;
        } else if (iter_pitch > pitch) {
            higher = i;
            break;
        }
    }
    struct note *note = create_note();
    note->oct = oct;
    note->key = key;
    insert_note_before(beat, note, higher);
    return VALID_NOTE;
}

////////////////////////////////////////////////////////////////////////
//                         Stage 5 Functions                          //
////////////////////////////////////////////////////////////////////////

// Cut a range of beats to the end of a track.
void cut_range_to_end(Track track, int range_length) {
    printf("cut_range_to_end not implemented yet.");
    return;
}

// Reverse a list of beats within a range of a track.
int reverse_range(Track track, int range_length) {
    printf("reverse_range not implemented yet.");
    return 0;
}