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

#include "tokenizer/File.h"
#include "utils/Utils.h"

#define MAX_INDEX 50

typedef struct {
    char* content;
    int size;
    int index;
    int arrayIndex;
    bool newLines;
    char* path;
    FILE* file;
} OpenFile;

typedef struct {
    int fileIndex;
    int index;
} FilePointer;

typedef struct {
    FilePointer name;
    FilePointer code;
} Define;

typedef struct {
    int fileIndex;
    int defineIndex;
    OpenFile files[MAX_INDEX];
    Define defines[MAX_INDEX];
    FilePointer readIndex;
    FileError error;
} OpenFiles;

static OpenFiles files;
static int lastChar = 0;
static int stackIndex = 0;
static FilePointer stack[MAX_INDEX];

static void fAdd(OpenFile* of, const void* data, int size) {
    while(of->index + size > of->size) {
        of->size *= 2;
        of->content = realloc(of->content, of->size);
    }
    memcpy(of->content + of->index, data, size);
    of->index += size;
}

static void fAddChar(OpenFile* of, int ic) {
    char c = ic;
    fAdd(of, &c, 1);
}

static int fReserverInt(OpenFile* of) {
    int address = of->index;
    int empty = 0;
    fAdd(of, &empty, sizeof(int));
    return address;
}

static void fSetInt(OpenFile* of, int address, int i) {
    memcpy(of->content + address, &i, sizeof(int));
}

static int fReadInt(OpenFile* of, int address) {
    int i = 0;
    memcpy(&i, of->content + address, sizeof(int));
    of->index += sizeof(int);
    return i;
}

static int fGet(OpenFile* of) {
    int c = fgetc(of->file);
    if(!of->newLines && c == '\n') {
        return ' ';
    }
    return c;
}

static bool fReadCommandString(OpenFile* of, char* buffer, int size) {
    int index = 0;
    int c = fGet(of);
    while(c == ' ') {
        c = fGet(of);
    }
    int text = 0;
    while(true) {
        if(c == EOF) {
            files.error("unexpected end of file");
        } else if(index >= size - 1) {
            files.error("unknown too long command");
        } else if(c == '"' && text < 2) {
            text++;
            buffer[index++] = c;
        } else if((isLetter(c) || text == 1) && text < 2) {
            buffer[index++] = c;
        } else if(c == ' ' || c == '\n') {
            buffer[index] = '\0';
            return c == '\n';
        } else {
            files.error("unexpected character '%c'", (char)c);
        }
        c = fGet(of);
    }
}

static const char* fGetDefineName(Define* d) {
    return files.files[d->name.fileIndex].content + d->name.index;
}

static int fStartDefine(OpenFile* of, bool* newLine) {
    fAddChar(of, '#');
    int end = fReserverInt(of);
    int nameFileIndex = fReserverInt(of);
    int nameIndex = fReserverInt(of);
    int codeFileIndex = fReserverInt(of);
    int codeIndex = fReserverInt(of);

    char command[64];
    *newLine = fReadCommandString(of, command, 64);
    fSetInt(of, nameFileIndex, of->arrayIndex);
    fSetInt(of, nameIndex, of->index);
    fAdd(of, command, strlen(command) + 1);

    fSetInt(of, codeFileIndex, of->arrayIndex);
    fSetInt(of, codeIndex, of->index);
    return end;
}

static void fFinishDefine(OpenFile* of, int end, int newLines) {
    fAddChar(of, '\0');
    fSetInt(of, end, of->index);
    for(int i = 0; i < newLines; i++) {
        fAddChar(of, '\n');
    }
}

static void fDefine(OpenFile* of) {
    bool newLine = false;
    int end = fStartDefine(of, &newLine);
    int newLines = newLine;
    while(true) {
        int c = fGet(of);
        if(c == '#') {
            char end[64];
            newLines += fReadCommandString(of, end, 64);
            if(strcmp(end, "end") == 0) {
                break;
            }
            files.error("invalid command '%s' inside define region", end);
        } else if(c == EOF) {
            files.error("unclosed #define");
        }
        if(c == '\n') {
            newLines++;
            c = ' ';
        }
        fAddChar(of, c);
    }
    fFinishDefine(of, end, newLines);
}

static void fReadFile(const char* path, bool newLines);
static void fEnter(FilePointer* fp);

static int fConcat(char* buffer, int size, const char* s) {
    int l = strlen(s) + 1;
    if(l > size) {
        files.error("too long include path");
    }
    memcpy(buffer, s, l);
    return l;
}

static void fInclude(OpenFile* of) {
    char path[64];
    if(fReadCommandString(of, path, 64)) {
        fAddChar(of, '\n');
    }
    int l = strlen(path);
    if(l < 2 || path[0] != '"' || path[l - 1] != '"') {
        files.error("invalid include path '%s'", path);
    }
    path[l - 1] = '\0';
    const char* cutPath = path + 1;

    char fullName[256];
    int index = fConcat(fullName, 256, of->path);
    while(index > 0 && fullName[index - 1] != '/') {
        index--;
    }
    fConcat(fullName + index, 256 - index, cutPath);

    FilePointer fp = {files.fileIndex, 0};
    fEnter(&fp);
    fReadFile(fullName, false);
}

static void fReadCommand(OpenFile* of) {
    char command[64];
    fReadCommandString(of, command, 64);
    if(strcmp(command, "define") == 0) {
        fDefine(of);
    } else if(strcmp(command, "include") == 0) {
        fInclude(of);
    } else {
        files.error("invalid command '%s'", command);
    }
}

static void fReadFile(const char* path, bool newLines) {
    if(files.fileIndex >= MAX_INDEX) {
        files.error("cannot read file '%s': too many open files", path);
    }
    OpenFile* of = files.files + files.fileIndex;
    of->arrayIndex = files.fileIndex++;
    of->index = 0;
    of->size = 16;
    of->newLines = newLines;
    of->content = malloc(of->size);
    of->file = fopen(path, "r");
    of->path = strdup(path);
    if(of->file == NULL) {
        files.error("cannot read file '%s'", path);
    }
    while(true) {
        int c = fGet(of);
        if(c == '#') {
            fReadCommand(of);
            continue;
        }
        fAddChar(of, c);
        if(c == EOF) {
            break;
        }
    }
    fAddChar(of, '\0');
}

void fOpen(const char* path, FileError fe) {
    files.fileIndex = 0;
    files.defineIndex = 0;
    files.readIndex.fileIndex = 0;
    files.readIndex.index = 0;
    files.error = fe;
    lastChar = 0;
    stackIndex = 0;
    fReadFile(path, true);
}

void fClose() {
    for(int i = 0; i < files.fileIndex; i++) {
        if(files.files[i].file != NULL) {
            fclose(files.files[i].file);
        }
        free(files.files[i].path);
        free(files.files[i].content);
    }
}

static OpenFile* currentFile() {
    return files.files + files.readIndex.fileIndex;
}

static int fReadChar() {
    return currentFile()->content[files.readIndex.index];
}

static bool fCompare(const char* a, const char* b, unsigned int bLength) {
    return strncmp(a, b, bLength) == 0 && strlen(a) == bLength;
}

static void fEnter(FilePointer* fp) {
    if(stackIndex >= MAX_INDEX) {
        files.error("define stack overflow");
    }
    stack[stackIndex++] = files.readIndex;
    files.readIndex = *fp;
}

static bool fCheckForReplacement() {
    OpenFile* of = currentFile();
    int start = files.readIndex.index;
    int index = start;
    while(index < of->index && isLetter(of->content[index])) {
        index++;
    }
    for(int i = 0; i < files.defineIndex; i++) {
        Define* d = files.defines + i;
        const char* name = fGetDefineName(d);
        if(fCompare(name, of->content + start, index - start)) {
            files.readIndex.index = index;
            fEnter(&d->code);
            return true;
        }
    }
    return false;
}

static void fReadDefine() {
    int base = files.readIndex.index + 1;
    int end = fReadInt(currentFile(), base);
    int nameFileIndex = fReadInt(currentFile(), base + sizeof(int));
    int nameIndex = fReadInt(currentFile(), base + sizeof(int) * 2);
    int codeFileIndex = fReadInt(currentFile(), base + sizeof(int) * 3);
    int codeIndex = fReadInt(currentFile(), base + sizeof(int) * 4);

    const char* name = files.files[nameFileIndex].content + nameIndex;

    if(files.defineIndex >= MAX_INDEX) {
        files.error("too many defines");
    }
    Define* d = files.defines + files.defineIndex++;
    for(int i = 0; i < files.defineIndex - 1; i++) {
        if(strcmp(name, fGetDefineName(files.defines + i)) == 0) {
            d = files.defines + i;
            files.defineIndex--;
            break;
        }
    }
    d->name.fileIndex = nameFileIndex;
    d->name.index = nameIndex;
    d->code.fileIndex = codeFileIndex;
    d->code.index = codeIndex;

    files.readIndex.index = end;
}

static void fPrepareChar() {
    while(true) {
        int c = fReadChar();
        if(c == '\0') {
            if(stackIndex <= 0) {
                files.error("define stack underflow");
            }
            files.readIndex = stack[--stackIndex];
        } else if(c == EOF && stackIndex > 0) {
            files.readIndex = stack[--stackIndex];
        } else if(c == '#') {
            fReadDefine();
        } else if(isLetter(c) && !isLetter(lastChar)) {
            if(fCheckForReplacement()) {
                continue;
            }
            break;
        } else {
            break;
        }
    }
}

static int fReadI() {
    fPrepareChar();
    lastChar = fReadChar();
    return currentFile()->content[files.readIndex.index++];
}

int fRead() {
    int i = fReadI();
    // putchar(i);
    return i;
}

int fPeek() {
    fPrepareChar();
    return fReadChar();
}

bool fReadIf(int c) {
    if(fPeek() == c) {
        fRead();
        return true;
    }
    return false;
}