/* 
 * Copyright (C) 2026 Peter Mikkelsen <petermikkelsen10@gmail.com>
 *
 * This file is part of aplwc.
 *
 * Aplwc is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Aplwc is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with aplwc.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "aplwc_internal.h"
static struct module_member *
add_member(struct aplwc *aplwc, struct aplwc_module *module, symbol_t name, struct module_member *real_member, int export)
{
	struct module_member *m;
	MEMPTRS(aplwc, 2);
	MEMPTR(0, module);
	MEMPTR(1, real_member);

	for(m = module->members; m; m = m->link){
		if(m->name == name){
			if(real_member)
				assert(m->real_member == NULL || m->real_member == real_member);
			m->real_member = real_member;
			m->exported |= export;
			goto end;
		}
	}

	if((m = memory_alloc_module_member(aplwc)) == NULL)
		goto end;

	m->module = module;
	m->exported = export;
	m->name = name;
	m->real_member = real_member;
	m->link = module->members;
	module->members = m;
end:
	MEMPTRS_EXIT(aplwc);
	return m;
}

static int
read_keyword_decl(struct aplwc *aplwc, struct aplwc_module *module, size_t offset)
{
	int len;
	size_t max;
	struct module_member *m;

	MEMPTRS(aplwc, 2);
	MEMPTR(0, module);

	m = NULL;
	MEMPTR(1, m);

#define t(n) module->tokens->tokens[offset+(n)]

	max = module->tokens->length - offset - 1;

	len = -1;
	assert(t(0).tag == TOKEN_TAG_KEYWORD);
	switch(t(0).data.keyword){
	case KW_MODULE:
		if((max < 1) || (t(1).tag != TOKEN_TAG_IDENTIFIER))
			goto fail_syntax;
		len = 1;
		break;
	case KW_SYMBOL:
		if((max < 1) || (t(1).tag != TOKEN_TAG_IDENTIFIER))
			goto fail_syntax;
		if((max < 2) || (t(2).tag != TOKEN_TAG_UNKNOWN_SYM))
			goto fail_syntax;
		len = 2;

		if((m = add_member(aplwc, module, t(1).data.symbol, NULL, 0)) == NULL)
			goto fail_other;
		if(add_member(aplwc, module, t(2).data.symbol, m, 0) == NULL)
			goto fail_other;
		break;
	case KW_EXPORT:
		for(len = 1; (size_t)len < max; len++){
			switch(t(len).tag){
			case TOKEN_TAG_UNKNOWN_SYM:
			case TOKEN_TAG_IDENTIFIER:
				if(add_member(aplwc, module, t(len).data.symbol, NULL, 1) == NULL)
					goto fail_other;
				break;
			case TOKEN_TAG_NEWLINE:
				goto end;
			default:
fail_syntax:
				aplwc->last_error = APLWC_INVALID_SYNTAX;
fail_other:
				len = -1;
				goto end;
			}
		}
		break;
	}

	if(ALWAYS(len >= 0) && (max > (size_t)len))
		if(t(len+1).tag != TOKEN_TAG_NEWLINE)
			goto fail_syntax;
	len++; /* For the keyword itself */
end:
	MEMPTRS_EXIT(aplwc);
	return len;
#undef t
}

static int
read_function_decl(struct aplwc *aplwc, struct aplwc_module *module, size_t offset)
{
	int len, ok;

	ok = 0;
	for(len = 1; (offset + len) < module->tokens->length; len++){
		if(module->tokens->tokens[offset+len].tag == TOKEN_TAG_DEL){
			ok = 1;
			break;
		}
	}
	if(!ok){
		len = -1;
		aplwc->last_error = APLWC_INVALID_SYNTAX;
	}
	return len;
}

static int
read_decl(struct aplwc *aplwc, struct aplwc_module *module, size_t offset)
{
	switch(module->tokens->tokens[offset].tag){
	case TOKEN_TAG_COMMENT:
	case TOKEN_TAG_NEWLINE:
		return 0;
	case TOKEN_TAG_KEYWORD:
		return read_keyword_decl(aplwc, module, offset);
	case TOKEN_TAG_DEL:
		return read_function_decl(aplwc, module, offset);
	default:
		aplwc->last_error = APLWC_INVALID_SYNTAX;
		return -1;
	}
}

static enum aplwc_rc
read_decls(struct aplwc *aplwc, struct aplwc_module *module)
{
	size_t offset;
	int skip;

	MEMPTRS(aplwc, 1);
	MEMPTR(0, module);

	for(offset = 0; offset < module->tokens->length; offset++){
		skip = read_decl(aplwc, module, offset);
		if(skip == -1)
			goto end;
		offset += skip;
	}

end:
	MEMPTRS_EXIT(aplwc);
	return aplwc->last_error;
}

struct aplwc_module *
module_lookup(struct aplwc *aplwc, struct string *name)
{
	struct aplwc_module *m;

	for(m = aplwc->modules; m; m = m->link){
		if(string_compare(m->name, name) == 0)
			break;
	}

	return m;
}

static enum aplwc_rc
resolve_imports(struct aplwc *aplwc, struct aplwc_module *module)
{
	struct aplwc_module *imported;
	struct string *name;
	struct module_member *m;
	enum aplwc_rc rc;

	MEMPTRS(aplwc, 3);
	MEMPTR(0, module);

	rc = APLWC_OK;
	if((name = chars_to_string(aplwc, "Boot", -1)) == NULL){
		rc = aplwc->last_error;
		goto end;
	}

	if((imported = module_lookup(aplwc, name)) == NULL)
		goto end; /* only because it is Boot for now... */
	MEMPTR(1, imported);
	m = NULL;
	MEMPTR(2, m);
	
	for(m = imported->members; m; m = m->link){
		if(m->exported == 0)
			continue;
		if(add_member(aplwc, module, m->name, m, 0) == NULL){
			rc = aplwc->last_error;
			goto end;
		}
	}
end:
	MEMPTRS_EXIT(aplwc);
	return rc;
}

enum aplwc_rc
load_module(struct aplwc *aplwc, struct string *name, struct token_list *tokens)
{
	struct aplwc_module *module;

	MEMPTRS(aplwc, 3);

	MEMPTR(0, name);
	MEMPTR(1, tokens);

	if((module = memory_alloc_aplwc_module(aplwc)) == NULL)
		goto end;

	MEMPTR(2, module);
	module->name = name;
	module->tokens = tokens;
	module->imports = NULL;
	module->members = NULL;
	module->link = NULL;

	if((aplwc->last_error = read_decls(aplwc, module)) != APLWC_OK)
		goto end;

	if((aplwc->last_error = resolve_imports(aplwc, module)) != APLWC_OK)
		goto end;

	if((aplwc->last_error = check_tokens(aplwc, module, tokens)) != APLWC_OK)
		goto end;

	module->link = aplwc->modules;
	aplwc->modules = module;

end:
	MEMPTRS_EXIT(aplwc);
	return aplwc->last_error;
}