/*
 * Copyright (c) 2025 Quinn Stephens and the OSMORA team.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS”
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdarg.h>
#include <stdio.h>
#include "lexer.h"
#include "log.h"
#include "parser.h"
#include "parser/ast.h"
#include "parser/types.h"

#define SYMS_HASHMAP_ROWS   16
#define PARAMS_HASHMAP_ROWS 4

static void
tok_error(struct token *tok, const char *fmt, ...)
{
    va_list args;

    fprintf(stderr, "\033[1;97m%d:%d: \033[1;91merror: \033[0m", tok->line, tok->col);
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
    va_end(args);
}

static void
tok_warn(struct token *tok, const char *fmt, ...)
{
    va_list args;

    fprintf(stderr, "\033[1;97m%d:%d: \033[1;95mwarning: \033[0m", tok->line, tok->col);
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
    va_end(args);
}

static struct type *
parse_type_ref(struct parser *ctx, int *ptr_levels_out)
{
    struct type *type;
    int ptr_levels;

    /*
     * TODO: Parse custom types.
     */
    if (!(ctx->tok.flags & TF_BUILTIN_TYPE)) {
        tok_error(&ctx->tok, "expected built-in type name\n");
        return NULL;
    }

    type = types_find_builtin(ctx->tok.kind);
    if (type == NULL) {
        return NULL;
    }

    parser_advance(ctx);
    ptr_levels = 0;
    while (ctx->tok.kind == TOK_ASTERISK) {
        ptr_levels++;
        parser_advance(ctx);
    }

    *ptr_levels_out = ptr_levels;
    return type;
}

static bool
parse_params(struct parser *ctx, struct ast_node *func)
{
    struct type *type;
    int ptr_levels;
    struct ast_node *node;

    func->params.rows = malloc(PARAMS_HASHMAP_ROWS * sizeof(struct list));
    if (func->params.rows == NULL) {
        return false;
    }

    func->params.row_count = PARAMS_HASHMAP_ROWS;
    hashmap_init(func->params);

    /*
     * TODO: Free memory if parsing parameters fails.
     */
    while (ctx->tok.kind != TOK_RPAREN) {
        type = parse_type_ref(ctx, &ptr_levels);
        if (type == NULL) {
            return false;
        }

        if (ctx->tok.kind != TOK_IDENTIFIER) {
            tok_error(&ctx->tok, "expected parameter name after type\n");
            return false;
        }

        node = malloc(sizeof(struct ast_node));
        if (node == NULL) {
            log_error("failed to allocate memory for AST node\n");
            return false;
        }

        node->kind = NOK_PARAMETER;
        node->name = ctx->tok.pos;
        node->name_len = ctx->tok.len;
        node->type = type;
        node->ptr_levels = ptr_levels;
        node->hashmap_entry.hash = ctx->tok.hash;
        hashmap_add(func->params, &node->hashmap_entry);

        parser_advance(ctx);
        if (ctx->tok.kind == TOK_COMMA) {
            parser_advance(ctx);
            if (ctx->tok.kind == TOK_RPAREN) {
                tok_warn(&ctx->tok, "extra \",\" at end of parameter list\n");
            }

            continue;
        }
    }

    return true;
}

static bool
parse_func_decl(struct parser *ctx, struct ast_node *func)
{
    func->kind = NOK_FUNCTION;

    /* Skip "void" marking no parameters */
    parser_advance(ctx);
    if (ctx->tok.kind == TOK_VOID) {
        parser_advance(ctx);
        if (ctx->tok.kind != TOK_RPAREN) {
            tok_error(&ctx->tok, "expected \")\" after \"void\"\n");
            free(func);
            return false;
        }
    }

    /* Parse parameters if present */
    if (ctx->tok.kind != TOK_RPAREN && !parse_params(ctx, func)) {
        free(func);
        return false;
    }

    parser_advance(ctx);
    if (ctx->tok.kind == TOK_SEMICOLON) {
        hashmap_add(ctx->syms, &func->hashmap_entry);
        parser_advance(ctx);
        return true;
    }

    if (ctx->tok.kind != TOK_LCURLY) {
        tok_error(&ctx->tok, "expected \";\" or \"{\" after \")\"\n");
        free(func);
        return false;
    }

    /*
     * TODO: Parse body.
     */
    parser_advance(ctx);
    if (ctx->tok.kind != TOK_RCURLY) {
        tok_error(&ctx->tok, "expected \"}\" after \"{\"\n");
        free(func);
        return false;
    }

    hashmap_add(ctx->syms, &func->hashmap_entry);
    parser_advance(ctx);
    return true;
}

static bool
parse_var_decl(struct parser *ctx, struct ast_node *var)
{
    var->kind = NOK_VARIABLE;

    /*
     * TODO: Parse initial value.
     */

    hashmap_add(ctx->syms, &var->hashmap_entry);
    parser_advance(ctx);
    return true;
}

static bool
parse_decl(struct parser *ctx)
{
    struct type *type;
    int ptr_levels;
    struct ast_node *node;

    type = parse_type_ref(ctx, &ptr_levels);
    if (type == NULL) {
        return false;
    }

    if (ctx->tok.kind != TOK_IDENTIFIER) {
        tok_error(&ctx->tok, "expected identifier after type\n");
        return false;
    }

    node = malloc(sizeof(struct ast_node));
    if (node == NULL) {
        log_error("failed to allocate memory for AST node\n");
        return false;
    }

    node->kind = NOK_UNKNOWN;
    node->name = ctx->tok.pos;
    node->name_len = ctx->tok.len;
    node->type = type;
    node->ptr_levels = ptr_levels;
    node->hashmap_entry.hash = ctx->tok.hash;

    parser_advance(ctx);
    if (ctx->tok.kind == TOK_LPAREN) {
        return parse_func_decl(ctx, node);
    } else if (ctx->tok.kind == TOK_SEMICOLON) {
        return parse_var_decl(ctx, node);
    }

    tok_error(&ctx->tok, "expected \"(\" or \";\" after identifier\n");
    free(node);
    return false;
}

bool
parser_parse(struct parser *ctx)
{
    bool success;

    log_debug("parsing...\n");

    if (!parser_advance(ctx)) {
        log_error("failed to get first token\n");
        return false;
    }

    ctx->syms.rows = malloc(SYMS_HASHMAP_ROWS * sizeof(struct list));
    if (ctx->syms.rows == NULL) {
        log_error("failed to allocate memory for symbol hashmap\n");
        return false;
    }

    ctx->syms.row_count = SYMS_HASHMAP_ROWS;
    hashmap_init(ctx->syms);

    while (ctx->tok.kind != TOK_EOF) {
        if (ctx->tok.kind == TOK_UNKNOWN) {
            tok_error(&ctx->tok, "unrecognized token\n");
            return false;
        }

        if ((ctx->tok.flags & TF_BUILTIN_TYPE) || ctx->tok.kind == TOK_IDENTIFIER) {
            success = parse_decl(ctx);
        }

        if (!success) {
            return false;
        }
    }

    return true;
}