#include "../include/parser.h"
#include "../include/ast.h"
#include "../include/compiler.h"
#include "../include/std/misc.h"
#include "../include/std/file.h"
#include "../include/std/mem.h"
#include "../include/std/log.h"
#include "../include/std/alloc.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

static CHECK_RESULT int parser_parse_rhs_start(Parser *self, Ast *rhs_expr);
static CHECK_RESULT int parser_parse_body(Parser *self, Ast *ast);
static CHECK_RESULT int parser_queue_file(Parser *self, BufferView path);

int parser_thread_data_init(ParserThreadData *self) {
    am_memset(&self->allocator, 0, sizeof(self->allocator));
    am_memset(&self->thread, 0, sizeof(self->thread));
    self->status = PARSER_THREAD_STATUS_NEW;
    return scoped_allocator_init(&self->allocator);
}

int parser_thread_data_deinit(ParserThreadData *self) {
    scoped_allocator_deinit(&self->allocator);
    return amal_thread_deinit(&self->thread);
}

int parser_thread_data_start(ParserThreadData *self, AmalThreadCallbackFunc callback_func, void *userdata) {
    return_if_error(amal_thread_deinit(&self->thread));
    return_if_error(amal_thread_create(&self->thread, AMAL_THREAD_JOINABLE, "Parser", callback_func, userdata));
    self->status = PARSER_THREAD_STATUS_RUNNING;
    return 0;
}

int parser_thread_data_join(ParserThreadData *self, void **result) {
    if(self->status == PARSER_THREAD_STATUS_NEW)
        return 0;
    return amal_thread_join(&self->thread, result);
}

int parser_init(Parser *self, amal_compiler *compiler, ScopedAllocator *allocator) {
    self->allocator = allocator;
    self->compiler = compiler;
    self->started = bool_false;
    self->error.index = 0;
    self->error.str = NULL;
    return buffer_init(&self->ast_objects, self->allocator);
}

static bool parser_got_overwritable_error(Parser *self) {
    return self->error.str != NULL;
}

/*
BODY_LOOP = BODY* @end_token
*/
static CHECK_RESULT int parser_parse_body_loop(Parser *self, Buffer *body_list, Token end_token) {
    for(;;) {
        Ast body_obj;
        bool is_end_token;
        return_if_error(tokenizer_consume_if(&self->tokenizer, end_token, &is_end_token));
        if(is_end_token)
            break;
        
        return_if_error(parser_parse_body(self, &body_obj));
        return_if_error(buffer_append(body_list, &body_obj, sizeof(body_obj)));
    }
    return PARSER_OK;
}

/*
LHS = 'const'|'var' IDENTIFIER
*/
static CHECK_RESULT int parser_parse_lhs(Parser *self, LhsExpr **result) {
    bool isConst;
    BufferView var_name;
    *result = NULL;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_CONST, &isConst));
    if(!isConst) {
        bool isVar;
        return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_VAR, &isVar));
        if(!isVar)
            return PARSER_OK;
    }

    return_if_error(tokenizer_accept(&self->tokenizer, TOK_IDENTIFIER));
    var_name = self->tokenizer.value.identifier;
    amal_log_debug("var name: %.*s", (int)var_name.size, var_name.data);
    return_if_error(scoped_allocator_alloc(self->allocator, sizeof(LhsExpr), (void**)result));
    lhsexpr_init(*result, isConst, var_name);
    return PARSER_OK;
}

/*
CLOSURE = 'fn' ('(' PARAM* ')')? '{' BODY_LOOP '}'
*/
static CHECK_RESULT int parser_parse_function_decl(Parser *self, FunctionDecl **func_decl) {
    bool match;
    *func_decl = NULL;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_FN, &match));
    if(!match)
        return PARSER_OK;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_OPEN_BRACE, &match));
    if(!match) {
        return_if_error(tokenizer_accept(&self->tokenizer, TOK_OPEN_PAREN));
        /* TODO: Parse parameters */
        return_if_error(tokenizer_accept(&self->tokenizer, TOK_CLOSING_PAREN));
        /* TODO: Parse return types */
        return_if_error(tokenizer_accept(&self->tokenizer, TOK_OPEN_BRACE));
    }

    return_if_error(scoped_allocator_alloc(self->allocator, sizeof(FunctionDecl), (void**)func_decl));
    return_if_error(funcdecl_init(*func_decl, self->allocator));

    return parser_parse_body_loop(self, &(*func_decl)->body, TOK_CLOSING_BRACE);
}

/*
FUNC_ARGS = (RHS_START)? (',' RHS_START)* ')'
*/
static CHECK_RESULT int parser_parse_function_args(Parser *self, FunctionCall *func_call) {
    bool first_arg;
    first_arg = bool_true;

    for(;;) {
        Ast arg_expr;
        bool is_end_token;
        arg_expr = ast_none();

        return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_CLOSING_PAREN, &is_end_token));
        if(is_end_token)
            break;
        
        if(!first_arg)
            return_if_error(tokenizer_accept(&self->tokenizer, TOK_COMMA));
        first_arg = bool_false;
        
        return_if_error(parser_parse_rhs_start(self, &arg_expr));
        return_if_error(buffer_append(&func_call->args, &arg_expr, sizeof(arg_expr)));
    }

    return PARSER_OK;
}

/*
VARIABLE = IDENTIFIER
FUNC_CALL_OR_VARIABLE = VARIABLE '(' FUNC_ARGS ')'
*/
static CHECK_RESULT int parser_parse_function_call_or_variable(Parser *self, Ast *expr) {
    bool match;
    BufferView identifier;
    FunctionCall *func_call;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_IDENTIFIER, &match));
    if(!match)
        return PARSER_OK;
    
    identifier = self->tokenizer.value.identifier;
    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_OPEN_PAREN, &match));
    if(!match) {
        Variable *variable;
        return_if_error(scoped_allocator_alloc(self->allocator, sizeof(Variable), (void**)&variable));
        variable->name = identifier;
        expr->type = AST_VARIABLE;
        expr->value.variable = variable;
        return PARSER_OK;
    }
    
    return_if_error(scoped_allocator_alloc(self->allocator, sizeof(FunctionCall), (void**)&func_call));
    return_if_error(funccall_init(func_call, self->tokenizer.value.identifier, self->allocator));
    expr->type = AST_FUNCTION_CALL;
    expr->value.func_call = func_call;
    return parser_parse_function_args(self, func_call);
}

/*
IMPORT = IMPORT_SYMBOL
*/
static CHECK_RESULT int parser_parse_import(Parser *self, Import **import) {
    bool match;
    *import = NULL;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_IMPORT, &match));
    if(!match)
        return PARSER_OK;
    
    return_if_error(scoped_allocator_alloc(self->allocator, sizeof(Import), (void**)import));
    import_init(*import, self->tokenizer.value.string);
    return PARSER_OK;
}

static CHECK_RESULT int parser_parse_number(Parser *self, Ast *rhs_expr) {
    bool match;
    Number *number;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_NUMBER, &match));
    if(!match)
        return PARSER_OK;
    
    return_if_error(scoped_allocator_alloc(self->allocator, sizeof(Number), (void**)&number));
    number_init(number, self->tokenizer.value.integer, self->tokenizer.number_is_integer);
    rhs_expr->type = AST_NUMBER;
    rhs_expr->value.number = number;
    return PARSER_OK;
}

/*
RHS = STRING | NUMBER | FUNC_CALL_OR_VARIABLE
*/
static CHECK_RESULT int parser_parse_rhs(Parser *self, Ast *rhs_expr) {
    bool match;

    return_if_error(tokenizer_consume_if(&self->tokenizer, TOK_STRING, &match));
    if(match) {
        String *string;
        return_if_error(scoped_allocator_alloc(self->allocator, sizeof(String), (void**)&string));
        return_if_error(string_init(string, self->tokenizer.value.string));
        rhs_expr->type = AST_STRING;
        rhs_expr->value.string = string;
        return PARSER_OK;
    }

    return_if_error(parser_parse_number(self, rhs_expr));
    if(rhs_expr->type != AST_NONE)
        return PARSER_OK;

    return_if_error(parser_parse_function_call_or_variable(self, rhs_expr));
    if(rhs_expr->type != AST_NONE)
        return PARSER_OK;

    self->error = tokenizer_create_error(&self->tokenizer, "Expected string, variable or function call");
    return PARSER_UNEXPECTED_TOKEN;
}

/*
RHS_START = CLOSURE | IMPORT | RHS
*/
int parser_parse_rhs_start(Parser *self, Ast *rhs_expr) {
    FunctionDecl *func_decl;
    Import *import;
    int result;

    return_if_error(parser_parse_function_decl(self, &func_decl));
    if(func_decl) {
        rhs_expr->type = AST_FUNCTION_DECL;
        rhs_expr->value.func_decl = func_decl;
        return PARSER_OK;
    }

    return_if_error(parser_parse_import(self, &import));
    if(import) {
        rhs_expr->type = AST_IMPORT;
        rhs_expr->value.import = import;
        return_if_error(parser_queue_file(self, import->path));
        return PARSER_OK;
    }

    result = parser_parse_rhs(self, rhs_expr);
    if(result == PARSER_UNEXPECTED_TOKEN && parser_got_overwritable_error(self))
        self->error = tokenizer_create_error(&self->tokenizer, "Expected string, variable, closure, function call or import");
    return result;
}

/*
BODY = (LHS '=' RHS_START) |
       RHS_START
*/
int parser_parse_body(Parser *self, Ast *ast) {
    LhsExpr *lhs_expr;
    Ast rhs_expr;
    rhs_expr = ast_none();

    return_if_error(parser_parse_lhs(self, &lhs_expr));
    if(lhs_expr)
        return_if_error(tokenizer_accept(&self->tokenizer, TOK_EQUALS));
    
    return_if_error(parser_parse_rhs_start(self, &rhs_expr));
    if(lhs_expr) {
        lhs_expr->rhs_expr = rhs_expr;
        ast->type = AST_LHS;
        ast->value.lhs_expr = lhs_expr;
    } else {
        *ast = rhs_expr;
    }
    return PARSER_OK;
}

/*
ROOT = BODY_LOOP
*/
int parser_parse_buffer(Parser *self, BufferView code_buffer, BufferView buffer_name) {
    int result;
    return_if_error(tokenizer_init(&self->tokenizer, code_buffer, buffer_name));
    result = parser_parse_body_loop(self, &self->ast_objects, TOK_END_OF_FILE);
    if(self->error.str != NULL)
        tokenizer_print_error_object(&self->tokenizer, &self->error);
    return result;
}

int parser_parse_file(Parser *self, BufferView filepath) {
    int result;
    char *file_data;
    usize file_size;
    char *filepath_tmp;

    amal_log_debug("Parsing %.*s", (int)filepath.size, filepath.data);
    assert(!self->started && "Parser can't be reused. Create a new parser.");
    self->started = bool_true;
    /* TODO: Somehow free this... */
    /*return_if_error(scoped_allocator_alloc(self->allocator, filepath.size + 1, (void**)&filepath_tmp));*/
    filepath_tmp = malloc(filepath.size + 1);
    am_memcpy(filepath_tmp, filepath.data, filepath.size);
    filepath_tmp[filepath.size] = '\0';
    result = read_whole_file(filepath_tmp, &file_data, &file_size);
    if(result != 0) return result;
    result = parser_parse_buffer(self, create_buffer_view(file_data, file_size), create_buffer_view(filepath_tmp, filepath.size));
    /* TODO: Somehow free this.. causes issue where filepath becomes corrupt */
    /*am_free(file_data);*/
    return result;
}

/*
Path can be path to included library path (or system library path) in which case
the path separator is a dot, otherwise the path separator is forward slash '/'
*/
int parser_queue_file(Parser *self, BufferView path) {
    /* TODO: Do not load same path twice or the compile will fail (and it can have recursive import) also for performance reasons */
    /* TODO: Parse special path (to include library path with dots) */
    return_if_error(amal_compiler_load_file(self->compiler, path));
    return PARSER_OK;
}