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

static const char** filters = NULL;
static int filterAmount = 0;
static char path[PATH_MAX] = {'\0'};
static int pathLength = 0;

typedef struct {
    char path[PATH_MAX];
    int lines;
} LineFile;

static LineFile* lineFiles = NULL;
static size_t lineFileIndex = 0;
static size_t lineFileCapacity = 0;

static void addLineFile(int lines) {
    while(lineFileIndex >= lineFileCapacity) {
        lineFileCapacity += 16;
        lineFiles = realloc(lineFiles, sizeof(LineFile) * lineFileCapacity);
    }
    LineFile* lf = lineFiles + lineFileIndex++;
    memcpy(lf->path, path, sizeof(path));
    lf->lines = lines;
}

static void appendToPath(const char* s) {
    for(int i = 0; pathLength < (PATH_MAX - 1) && s[i] != '\0'; i++) {
        path[pathLength++] = s[i];
    }
    path[pathLength] = '\0';
}

static int enterPath(const char* name) {
    int length = pathLength;
    appendToPath("/");
    appendToPath(name);
    return length;
}

static void resetPath(int marker) {
    path[marker] = '\0';
    pathLength = marker;
}

static void countLines(void) {
    FILE* file = fopen(path, "r");
    if(file == NULL) {
        return;
    }
    int lines = 0;
    while(1) {
        int c = fgetc(file);
        if(c == EOF) {
            lines++;
            break;
        } else if(c == '\n') {
            lines++;
        }
    }
    addLineFile(lines);
    fclose(file);
}

static void handleFile(const char* name) {
    size_t end = strlen(name);
    for(int i = 0; i < filterAmount; i++) {
        if(*filters[i] == '-') {
            continue;
        }
        size_t l = strlen(filters[i]);
        if(end >= l && !strcmp(filters[i], name + (end - l))) {
            int marker = enterPath(name);
            countLines();
            resetPath(marker);
            return;
        }
    }
}

static int isAllowedName(const char* name) {
    for(int i = 0; i < filterAmount; i++) {
        if(*filters[i] != '-') {
            continue;
        }
        if(!strcmp(name, filters[i] + 1)) {
            return 0;
        }
    }
    return 1;
}

static void scanFolder(void) {
    DIR* dir = opendir(path);
    if(dir == NULL) {
        return;
    }
    while(1) {
        struct dirent* entry = readdir(dir);
        if(entry == NULL) {
            break;
        } else if(!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..")) {
            continue;
        } else if(entry->d_type == DT_DIR) {
            const char* name = entry->d_name;
            if(isAllowedName(name)) {
                int marker = enterPath(name);
                scanFolder();
                resetPath(marker);
            }
        } else if(entry->d_type == DT_REG) {
            handleFile(entry->d_name);
        }
    }
    closedir(dir);
}

static int compareLineFiles(const void* a, const void* b) {
    const LineFile* lnA = a;
    const LineFile* lnB = b;
    if(lnA->lines < lnB->lines) {
        return -1;
    }
    return lnA->lines == lnB->lines ? 0 : 1;
}

int main(int argAmount, const char** args) {
    if(argAmount < 3) {
        puts("Use '-' before a name to exclude such paths");
        if(argAmount > 0) {
            printf("%s <path> <ending_1> [ending_2] ...\n", args[0]);
        } else {
            puts("... <path> <ending_1> [ending_2] ...");
        }
        return 0;
    }
    filters = args + 2;
    filterAmount = argAmount - 2;
    appendToPath(args[1]);
    scanFolder();

    qsort(lineFiles, lineFileIndex, sizeof(LineFile), compareLineFiles);

    int allLines = 0;
    for(size_t i = 0; i < lineFileIndex; i++) {
        LineFile* ln = lineFiles + i;
        printf("%6d | %s\n", ln->lines, ln->path);
        allLines += ln->lines;
    }
    printf("Lines: %d\n", allLines);

    free(lineFiles);
    return 0;
}