#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>

#define THROWABLE CHECK_RESULT int
#define try(result) \
do { \
    int return_if_result; \
    return_if_result = (result); \
    (void)return_if_result; \
} while(0)
#define throw(result) do { longjmp(self->parse_env, (result)); } while(0)
#define throw_if_error(result) \
do { \
    int return_if_result; \
    return_if_result = (result); \
    if((return_if_result) != 0) \
        throw(return_if_result); \
} while(0)

static THROWABLE parser_parse_rhs_start(Parser *self, Ast *rhs_expr);
static THROWABLE parser_parse_body(Parser *self, Ast *ast);
static THROWABLE 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;
    self->error_context = ERROR_CONTEXT_NONE;
    /* TODO: When resolving ast uses mutex, add compiler->scope as the parent of the parser scope */
    self->current_scope = &self->scope;
    return scope_init(&self->scope, NULL, self->allocator);
}

/*
BODY_LOOP = BODY* @end_token
*/
static THROWABLE parser_parse_body_loop(Parser *self, Scope *scope, Token end_token) {
    int result;
    for(;;) {
        Ast body_obj;
        bool is_end_token;
        throw_if_error(tokenizer_consume_if(&self->tokenizer, end_token, &is_end_token));
        if(is_end_token)
            break;
        
        try(parser_parse_body(self, &body_obj));
        result = scope_add_child(scope, &body_obj);
        if(result == 0) {
            continue;
        } else if(result == AST_ERR_DEF_DUP) {
            /* TODO: Convert ast type to string for error message */
            BufferView obj_name;
            obj_name = ast_get_name(&body_obj);
            self->error = tokenizer_create_error(&self->tokenizer, 
                                                tokenizer_get_code_reference_index(&self->tokenizer, obj_name.data),
                                                "Variable with the name %.*s was declared twice in the same scope", obj_name.size, obj_name.data);
            self->error_context = ERROR_CONTEXT_NONE;
            throw(result);
        } else {
            throw(result);
        }
    }
    return PARSER_OK;
}

/*
VAR_TYPE_DEF = ':' TOK_IDENTIFIER
*/
static THROWABLE parser_parse_var_type_def(Parser *self, BufferView *type_name) {
    bool match;
    throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_COLON, &match));
    if(match) {
        throw_if_error(tokenizer_accept(&self->tokenizer, TOK_IDENTIFIER));
        *type_name = self->tokenizer.value.identifier;
    }
    return PARSER_OK;
}

/*
LHS =   ('const' TOK_IDENTIFIER VAR_TYPE_DEF? '=') |
        ('var' TOK_IDENTIFIER VAR_TYPE_DEF? '='|';')
*/
static THROWABLE parser_parse_lhs(Parser *self, LhsExpr **result, bool *assignment_or_rhs) {
    bool is_const;
    bool match;
    BufferView var_name;
    *result = NULL;
    *assignment_or_rhs = bool_true;

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

    throw_if_error(tokenizer_accept(&self->tokenizer, TOK_IDENTIFIER));
    var_name = self->tokenizer.value.identifier;
    throw_if_error(scoped_allocator_alloc(self->allocator, sizeof(LhsExpr), (void**)result));
    lhsexpr_init(*result, is_const, var_name);

    try(parser_parse_var_type_def(self, &(*result)->type_name));

    throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_EQUALS, &match));
    if(match) {
        *assignment_or_rhs = bool_true;
        return PARSER_OK;
    }
    
    *assignment_or_rhs = bool_false;
    throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_SEMICOLON, &match));
    if(match && is_const) {
        self->error = tokenizer_create_error(&self->tokenizer,
                                            tokenizer_get_error_index(&self->tokenizer),
                                            "const variable declaration requires assignment (expected '=', got ';')");
        throw(PARSER_UNEXPECTED_TOKEN);
    }
    if(!match) {
        self->error = tokenizer_create_error(&self->tokenizer,
                                            tokenizer_get_error_index(&self->tokenizer),
                                            "Expected '=' or ';'");
        throw(PARSER_UNEXPECTED_TOKEN);
    }
    return PARSER_OK;
}

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

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

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

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

    prev_scope = self->current_scope;
    self->current_scope = &(*func_decl)->body;
    try(parser_parse_body_loop(self, self->current_scope, TOK_CLOSING_BRACE));
    self->current_scope = (*func_decl)->body.parent;
    assert(self->current_scope == prev_scope);
    return PARSER_OK;
}

/*
FUNC_ARGS = (RHS_START)? (',' RHS_START)* ')'
*/
static THROWABLE 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();

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

    return PARSER_OK;
}

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

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

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

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

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

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

/*
RHS_S = STRING | NUMBER | FUNC_CALL_OR_VARIABLE
*/
static THROWABLE parser_parse_rhs_single_expr(Parser *self, Ast *rhs_expr) {
    bool match;
    *rhs_expr = ast_none();

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

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

    try(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,
                                        tokenizer_get_error_index(&self->tokenizer),
                                        "Expected string, variable or function call");
    throw(PARSER_UNEXPECTED_TOKEN);
}

static THROWABLE parser_parse_rhs_binop(Parser *self, Ast *expr);

/*
RHS_BINOP_OPT_PAREN = RHS_S | '(' RHS_BINOP ')'
*/
static THROWABLE parser_parse_rhs_binop_opt_paren(Parser *self, Ast *expr) {
    bool match;
    throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_OPEN_PAREN, &match));
    if(!match) {
        try(parser_parse_rhs_single_expr(self, expr));
        return PARSER_OK;
    }

    try(parser_parse_rhs_binop(self, expr));
    throw_if_error(tokenizer_accept(&self->tokenizer, TOK_CLOSING_PAREN));
    if(expr->type == AST_BINOP)
        expr->value.binop->grouped = bool_true;

    return PARSER_OK;
}

/*
RHS_BINOP = RHS_BINOP_OPT_PAREN (TOK_BINOP RHS_BINOP_OPT_PAREN)?

Note: Parantheses count has to match for the beginning paranthesis and the ending parenthesis.
*/
int parser_parse_rhs_binop(Parser *self, Ast *expr) {
    bool match;
    Ast lhs;
    Ast rhs;
    BinopType binop_type;
    Binop *binop;

    try(parser_parse_rhs_binop_opt_paren(self, &lhs));
    throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_BINOP, &match));
    if(!match) {
        *expr = lhs;
        return PARSER_OK;
    }
    binop_type = self->tokenizer.value.binop_type;

    try(parser_parse_rhs_binop(self, &rhs));
    throw_if_error(scoped_allocator_alloc(self->allocator, sizeof(Binop), (void**)&binop));
    binop_init(binop);
    binop->type = binop_type;
    binop->lhs = lhs;
    binop->rhs = rhs;
    ast_init(expr, binop, AST_BINOP);
    return PARSER_OK;
}

/*
RHS = RHS_BINOP ';'

Note: Parantheses count has to match for the beginning paranthesis and the ending parenthesis.
*/
static THROWABLE parser_parse_rhs(Parser *self, Ast *rhs_expr) {
    /* TODO: If binop only contains one expression, then use that directly for @rhs_expr */
    try(parser_parse_rhs_binop(self, rhs_expr));

    /* TODO: Implement this */
    /*binop_reorder_by_precedence(binop);*/
    return PARSER_OK;
}

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

    try(parser_parse_function_decl(self, &func_decl));
    if(func_decl) {
        ast_init(rhs_expr, func_decl, AST_FUNCTION_DECL);
        return PARSER_OK;
    }

    try(parser_parse_import(self, &import));
    if(import) {
        ast_init(rhs_expr, import, AST_IMPORT);
        try(parser_queue_file(self, import->path));
        return PARSER_OK;
    }

    self->error_context = ERROR_CONTEXT_RHS_START;
    try(parser_parse_rhs(self, rhs_expr));
    self->error_context = ERROR_CONTEXT_NONE;
    return PARSER_OK;
}

/*
BODY_SEMICOLON = ';'

Note: Semicolon is not required for closures, structs and tables
*/
static THROWABLE parser_parse_body_semicolon(Parser *self, Ast *expr) {
    if(expr->type == AST_BINOP) {
        bool match;
        throw_if_error(tokenizer_consume_if(&self->tokenizer, TOK_SEMICOLON, &match));
        if(!match) {
            /* TODO: Specify all the binop characters instead of "binop" which doesn't make sense for the user */
            self->error = tokenizer_create_error(&self->tokenizer,
                                                tokenizer_get_error_index(&self->tokenizer),
                                                "Expected ';' or binop");
            throw(PARSER_UNEXPECTED_TOKEN);
        }
        return PARSER_OK;
    }

    /* TODO: Check for struct and tables */
    if(expr->type != AST_FUNCTION_DECL)
        throw_if_error(tokenizer_accept(&self->tokenizer, TOK_SEMICOLON));
    
    return PARSER_OK;
}

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

    try(parser_parse_lhs(self, &lhs_expr, &assignment_or_rhs));
    if(!assignment_or_rhs) {
        ast_init(ast, lhs_expr, AST_LHS);
        return PARSER_OK;
    }
    
    try(parser_parse_rhs_start(self, &rhs_expr));
    if(lhs_expr) {
        lhs_expr->rhs_expr = rhs_expr;
        ast_init(ast, lhs_expr, AST_LHS);
    } else {
        *ast = rhs_expr;
    }

    try(parser_parse_body_semicolon(self, &rhs_expr));
    return PARSER_OK;
}

/*
ROOT = BODY_LOOP
*/
int parser_parse_buffer(Parser *self, BufferView code_buffer, BufferView buffer_name) {
    int result;
    throw_if_error(tokenizer_init(&self->tokenizer, self->allocator, code_buffer, buffer_name));
    result = setjmp(self->parse_env);
    if(result == 0)
        try(parser_parse_body_loop(self, &self->scope, TOK_END_OF_FILE));
    else if(self->error.str != NULL) {
        switch(self->error_context) {
            case ERROR_CONTEXT_NONE:
                tokenizer_print_error_object(&self->tokenizer, &self->error);
                break;
            case ERROR_CONTEXT_RHS_START:
                tokenizer_print_error(&self->tokenizer, self->tokenizer.prev_index, "Expected string, variable, closure, function call or import");
                break;
            default:
                assert(bool_false && "Error context handling not implemented");
                break;
        }
    }
    assert(self->current_scope == &self->scope);
    return result;
}

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

    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;
    assert(filepath.size > 0 && filepath.data[filepath.size] == '\0');
    result = read_whole_file(filepath.data, &file_data, &file_size);
    if(result != 0) return result;
    result = parser_parse_buffer(self, create_buffer_view(file_data, file_size), filepath);
    return result;
}

static CHECK_RESULT int file_path_join(BufferView directory, BufferView file, ScopedAllocator *allocator, Buffer *result) {
    return_if_error(buffer_init(result, allocator));
    return_if_error(buffer_append(result, NULL, directory.size + 1 + file.size + 1));
    am_memcpy(result->data, directory.data, directory.size);
    result->data[directory.size] = '/';
    am_memcpy(result->data + directory.size + 1, file.data, file.size);
    result->data[directory.size + 1 + file.size] = '\0';
    return 0;
}

/*
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) */
    BufferView file_directory;
    BufferView filename;
    Buffer file_to_parse;
    file_directory = file_get_parent_directory(self->tokenizer.code_name);
    filename = file_get_name(path);
    return_if_error(file_path_join(file_directory, filename, self->allocator, &file_to_parse));
    /*
    We want buffer to be null terminated but null terminated character
    should not be included for the length.
    */
    throw_if_error(amal_compiler_load_file(self->compiler, create_buffer_view(file_to_parse.data, file_to_parse.size - 1)));
    return PARSER_OK;
}