#include "file.h"
#include <errno.h>
#include <stdio.h>
#include <string.h>

ResultType(int64_t, objectPtr) impl_File_INIT(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];

    cometSetField(fileObj, 0, args[1]); // self.path = path

    char* path = cometArgString(args[1]);
    char* mode = cometArgString(args[2]);

    FILE* f = fopen(path, mode);
    if (!f) {
        char* buffer = malloc(128);
        snprintf(buffer, 128, "Failed to open \"%s\": %s", path, strerror(errno));
        return cometError(vm, "IOFail", buffer);
    }

    cometSetField(fileObj, 2, (int64_t)f); // self.ptr = f

    // seek to end
    fseek(f, 0L, SEEK_END);
    int64_t size = ftell(f);
    rewind(f);

    cometSetField(fileObj, 3, size); // self.size = size

    return Success(int64_t, objectPtr, (int64_t)fileObj);
}

ResultType(int64_t, objectPtr) impl_readAll(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];

    FILE* f = (FILE*)fileObj->fields[2];
    int64_t length = fileObj->fields[3];

    if (length == 0) {
        return Success(int64_t, objectPtr, cometSerializeString(""));
    }

    char* content = calloc(length + 1, 1);
    if (!content) {
        return cometError(vm, "MemoryAllocFail", "Failed to allocate memory for file content. (impl_readAll)");
    }

    fread(content, length, 1, f);

    // serialize string
    return Success(int64_t, objectPtr, cometSerializeString(content));
}

ResultType(int64_t, objectPtr) impl_read(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[1];

    int64_t amountToRead = cometArgBig(args[0]);

    FILE* f = (FILE*)fileObj->fields[2];

    char* content = calloc(amountToRead + 1, 1);
    if (!content) {
        return cometError(vm, "MemoryAllocFail", "Failed to allocate memory for file content. (impl_read)");
    }

    size_t bytesRead = fread(content, amountToRead, 1, f);
    if (bytesRead < amountToRead) {
        if (ferror(f)) {
            char* buffer = malloc(128);
            snprintf(buffer, 128, "Error while reading file: %s", strerror(errno));
            return cometError(vm, "IOFail", buffer);
        }
    }

    // serialize string
    return Success(int64_t, objectPtr, cometSerializeString(content));
}

ResultType(int64_t, objectPtr) impl_readln(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];

    FILE* f = (FILE*)fileObj->fields[2];

     if (feof(f)) {
        return Success(int64_t, objectPtr, cometSerializeString(""));
    }

    char* line = NULL;
    size_t len = 0;
    ssize_t read = getline(&line, &len, f);

    if (read == -1) {
        if (ferror(f)) {
            char* buffer = malloc(128);
            snprintf(buffer, 128, "Error while reading line: %s", strerror(errno));
            return cometError(vm, "IOFail", buffer);
        } else {
            return Success(int64_t, objectPtr, cometSerializeString(""));
        }
    }

    if (read > 0 && line[read - 1] == '\n') {
        line[read - 1] = 0;
    }

    // serialize string
    return Success(int64_t, objectPtr, cometSerializeString(line));
}

ResultType(int64_t, objectPtr) impl_isEOF(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];

    FILE* f = (FILE*)fileObj->fields[2];

    return Success(int64_t, objectPtr, feof(f));
}

ResultType(int64_t, objectPtr) impl_write(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[1];

    FILE* f = (FILE*)fileObj->fields[2];

    char* strToWrite = cometArgString(args[0]);
    size_t numBytes = strlen(strToWrite);

    size_t written = fwrite(strToWrite, numBytes, 1, f);
    if (written < numBytes) {
        if (ferror(f)) {
            char* buffer = malloc(128);
            snprintf(buffer, 128, "Error while writing to file: %s", strerror(errno));
            return cometError(vm, "IOFail", buffer);
        }
    }

    return Success(int64_t, objectPtr, 0);
}

ResultType(int64_t, objectPtr) impl_writeln(int64_t* args, CometVM* vm) {
    char* strToWrite = cometArgString(args[0]);

    size_t ogStrLen = strlen(strToWrite);

    char* fullString = malloc( ogStrLen + 2); // 1 byte for \n, 1 byte for null
    memcpy(fullString, strToWrite, ogStrLen);
    fullString[ogStrLen]   = '\n';
    fullString[ogStrLen+1] = 0;

    size_t fullStringLen = ogStrLen + 1;

    CometObject* fileObj = (CometObject*)args[1];
    FILE* f = (FILE*)fileObj->fields[2];

    size_t written = fwrite(fullString, fullStringLen, 1, f);
    if (written < fullStringLen) {
        if (ferror(f)) {
            char* buffer = malloc(128);
            snprintf(buffer, 128, "Error while writing to file: %s", strerror(errno));
            return cometError(vm, "IOFail", buffer);
        }
    }

    return Success(int64_t, objectPtr, 0);
}

ResultType(int64_t, objectPtr) impl_seek(int64_t* args, CometVM* vm) {
    int64_t seekPos = cometArgBig(args[0]);

    CometObject* fileObj = (CometObject*)args[1];
    FILE* f = (FILE*)fileObj->fields[2];

    fseek(f, seekPos, SEEK_SET);

    return Success(int64_t, objectPtr, 0);
}

ResultType(int64_t, objectPtr) impl_tell(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];
    FILE* f = (FILE*)fileObj->fields[2];

    int64_t tellTo = ftell(f);
    if (tellTo == -1) {
        if (ferror(f)) {
            char* buffer = malloc(128);
            snprintf(buffer, 128, "Error while telling file: %s", strerror(errno));
            return cometError(vm, "IOFail", buffer);
        }
    }

    return Success(int64_t, objectPtr, tellTo);
}

ResultType(int64_t, objectPtr) impl_flush(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];
    FILE* f = (FILE*)fileObj->fields[2];

    fflush(f);

    return Success(int64_t, objectPtr, 0);
}

ResultType(int64_t, objectPtr) impl_close(int64_t* args, CometVM* vm) {
    CometObject* fileObj = (CometObject*)args[0];
    FILE* f = (FILE*)fileObj->fields[2];

    fclose(f);

    return Success(int64_t, objectPtr, 0);
}


void createFileStruct(CometEnvironment* env) {
    CometStruct* fileStruct = cometDefineStruct(env, "File", NULL);

    List(StructField) fields = newList(StructField);
    append(fields, cometCreateField("path", cometTypeString, FIELD_READ_ONLY));
    append(fields, cometCreateField("mode", cometTypeString, FIELD_READ_ONLY));
    append(fields, cometCreateField("ptr", cometTypeBig, FIELD_PRIVATE));
    append(fields, cometCreateField("size", cometTypeBig, FIELD_READ_ONLY));

    List(cometFuncPtr) methods = newList(cometFuncPtr);
    append(methods, cometDefineMethod(env, "readAll", fileStruct, cometTypeString, 0, false));
    append(methods, cometDefineMethod(env, "read", fileStruct, cometTypeString, 1, false, cometTypeBig));
    append(methods, cometDefineMethod(env, "readln", fileStruct, cometTypeString, 0, false));
    append(methods, cometDefineMethod(env, "isEOF", fileStruct, cometTypeBool, 0, false));
    append(methods, cometDefineMethod(env, "write", fileStruct, cometTypeVoid, 1, false, cometTypeString));
    append(methods, cometDefineMethod(env, "writeln", fileStruct, cometTypeVoid, 1, false, cometTypeString));
    append(methods, cometDefineMethod(env, "seek", fileStruct, cometTypeVoid, 1, false, cometTypeBig));
    append(methods, cometDefineMethod(env, "tell", fileStruct, cometTypeBig, 0, false));
    append(methods, cometDefineMethod(env, "flush", fileStruct, cometTypeVoid, 0, false));
    append(methods, cometDefineMethod(env, "close", fileStruct, cometTypeVoid, 0, false));

    cometSetStructFieldsAndMethods(fileStruct, fields, methods);
    cometDefineConstructor(env, fileStruct, 2, false, cometTypeString, cometTypeString);
}