/*
 * # catboot
 *
 * the bootstrap compiler for catskill,
 * implemented as simply as possible,
 * depending only on the C standard library,
 * in this case musl, and built statically
 * in a single union build.
 *
 * should only be used to compile `catskill` itself,
 * as it is not a full-featured compiler, and never will be.
 * once `catskill` can compile itself using a C backend,
 * this compiler version will be permanently retired.
 * (although that's still very far away!! have fun! :3)
 *
 * Copyright (c) 2025-2026, Mel G. <mel@rnrd.eu>
 *
 * SPDX-License-Identifier: MPL-2.0
 */

#define _POSIX_C_SOURCE 200809L

#include "catboot.h"

#define VERSION "0.0.0"

struct String
read_file(const ascii* path)
{
    struct stat stat_info;
    if (stat(path, &stat_info) == -1) failure("i couldn't open that file, sorry :(");

    check(stat_info.st_size > 0, "file is empty, i can't map an empty file");

    const int32 file_descriptor = open(path, O_RDONLY);
    check(file_descriptor != -1, "i couldn't open that file, sorry :(");

    const flags mmap_prot = PROT_READ;
    const flags mmap_flags = MAP_PRIVATE;
    const unknown* file_data =
        mmap(nil, stat_info.st_size, mmap_prot, mmap_flags, file_descriptor, 0);

    return string_from_static_c_string(file_data);
}

void
usage(void)
{
    fprintf(
        stderr,
        "usage:\n"
        "    catboot <filename>\n"
        "    catboot --test-lex <filename>\n"
        "    catboot --test-parse <filename>\n"
        "\n"
        "options:\n"
        "        --test-lex <file>\t output token stream for file\n"
        "        --test-parse <file>\t output abstract syntax tree for file in s-expr format\n"
        "        --test-transpile <file>\t output transpiled c language source from file\n"
        "    -?, --help\t\t\t print this help message\n"
        "    -v, --version\t\t print current version\n");
}

void
version(void)
{
    fprintf(
        stderr,
        "catboot (catskill), version " VERSION "\n"
        "\n"
        "This program's source code is subject to the terms of the Mozilla Public\n"
        "License, v. 2.0. If a copy of the MPL was not distributed with this\n"
        "file, You can obtain one at https://mozilla.org/MPL/2.0/.\n"
        "\n"
        "Copyright (c) 2025, Mel G. <mel@rnrd.eu>\n");
}

integer
debug_lex_pass(struct String source)
{
    struct Lexer lexer;
    lexer_new(&lexer, source);

    struct Token token;
    do {
        token = lexer_next(&lexer);
        token_debug_print(&token);
        printf(" ");
    } while (token.kind != TOKEN_END_OF_FILE);

    return 0;
}

integer
debug_parse_pass(struct Source_File source_file)
{
    struct Lexer lexer;
    lexer_new(&lexer, source_file.source);

    struct Parser parser;
    parser_new(&parser, &lexer, source_file);

    struct Tree tree;
    int parser_result = parser_do_your_thing(&parser, &tree);
    if (parser_result != 0) {
        log_error("parser finished with errors\n");
        return parser_result;
    }

    tree_printer(&tree);

    return parser_result;
}

integer
debug_transpile_pass(struct Source_File source_file)
{
    struct Lexer lexer;
    lexer_new(&lexer, source_file.source);

    struct Parser parser;
    parser_new(&parser, &lexer, source_file);

    struct Tree tree;
    int parser_result = parser_do_your_thing(&parser, &tree);
    if (parser_result != 0) {
        log_error("parser finished with errors\n");
        return parser_result;
    }

    struct Transpile_Output output = transpile_output_from_file(stdout);

    struct Transpiler transpiler;
    transpiler_new(&transpiler, output);
    return transpiler_catskill_to_c(&transpiler, &tree);
}

enum Command_Result
{
    COMMAND_OK,
    COMMAND_FAIL,
};

struct Command_Arguments
{
    const ascii* input;
    const ascii* output;
};

enum Command_Result
version_command(struct Command_Arguments* arguments)
{
    version();
    return COMMAND_OK;
}

enum Command_Result
help_command(struct Command_Arguments* arguments)
{
    usage();
    return COMMAND_OK;
}

enum Command_Result
test_lex_command(struct Command_Arguments* arguments)
{
    struct String source = read_file(arguments->input);

    // TODO: lexer errors
    debug_lex_pass(source);

    return COMMAND_OK;
}

enum Command_Result
test_parse_command(struct Command_Arguments* arguments)
{
    struct String source = read_file(arguments->input);
    struct Source_File source_file = {
        .source = source,
        .path = string_from_static_c_string(arguments->input),
    };

    if (debug_parse_pass(source_file)) return COMMAND_FAIL;

    return COMMAND_OK;
}

enum Command_Result
test_transpile_command(struct Command_Arguments* arguments)
{
    struct String source = read_file(arguments->input);
    struct Source_File source_file = {
        .source = source,
        .path = string_from_static_c_string(arguments->input),
    };

    if (debug_transpile_pass(source_file)) return COMMAND_FAIL;

    return COMMAND_OK;
}

struct String
output_name_from_input_name(struct String input)
{
    uint end = string_length(input);
    for (uint start = string_length(input) - 1; start > 0; --start) {
        switch (string_at(input, start)) {
        // we captured the file extension, we need to keep going until we find a slash,
        // but we move the end index to the current index first to exclude the extension.
        case '.':
            end = start;
            break;
        // we found a slash, so we captured the first part of the filename,
        // we can stop here.
        case '/':
            return string_slice(input, start + 1, end); // exclude the slash itself
        // otherwise, keep going.
        default:
            break;
        }
    }

    return string_slice(input, 0, end);
}

enum Command_Result
default_command(struct Command_Arguments* arguments)
{
    struct String source = read_file(arguments->input);
    struct Source_File source_file = {
        .source = source,
        .path = string_from_static_c_string(arguments->input),
    };

    struct Lexer lexer;
    lexer_new(&lexer, source);

    struct Parser parser;
    parser_new(&parser, &lexer, source_file);

    struct Tree tree;
    if (parser_do_your_thing(&parser, &tree) != 0) {
        log_error("parser finished with errors\n");
        return COMMAND_FAIL;
    }

    struct Transpiler transpiler;
    transpiler_new(&transpiler, transpile_output_from_string());

    if (transpiler_catskill_to_c(&transpiler, &tree) != 0) {
        log_error("transpiler finished with errors\n");
        return COMMAND_FAIL;
    }
    struct String transpiled_source = transpile_output_string(&transpiler.output);

    struct String output_file;
    if (arguments->output) {
        output_file = string_from_c_string(arguments->output);
    } else {
        output_file = output_name_from_input_name(source_file.path);
    }

    struct Build_Result build_result = build_executable(transpiled_source, output_file);
    if (!build_result.success) {
        log_error("backend failure with exit code %ld\n", build_result.compiler_exit_code);
        log_error(
            "compiler output:\n%.*s\n", (int)build_result.compiler_log.length,
            build_result.compiler_log.data);

        return COMMAND_FAIL;
    }

    log_debug("success! executable written to '%s'.\n", string_c_str(build_result.output_path));

    return COMMAND_OK;
}

typedef enum Command_Result (*Command_Function)(struct Command_Arguments*);

struct Command_Definition
{
    bool is_default;
    const ascii* name;
    const ascii short_name;
    Command_Function function;
};

struct Command_Definition command_definitions[] = {
    { .name = "test-lex", .function = test_lex_command },
    { .name = "test-parse", .function = test_parse_command },
    { .name = "test-transpile", .function = test_transpile_command },

    { .name = "version", .short_name = 'v', .function = version_command },
    { .name = "help", .short_name = '?', .function = help_command },

    { .is_default = true, .function = default_command },
};

int32
main(const int32 argc, ascii* argv[])
{
    if (argc < 2) {
        usage();
        return EXIT_FAILURE;
    }

    bool have_command = false;
    ascii *command_name = nil, short_command_name = '\0', *input = nil, *output = nil;
    for (uint a = 1; a < argc; ++a) {
        ascii* arg = argv[a];

        if (arg[0] == '-') {
            check(!have_command, "multiple commands given");
            if (arg[1] == '-') {
                check(!command_name, "multiple full-name commands given");
                command_name = &arg[2];
            } else {
                check(!short_command_name, "multiple short-name commands given");
                short_command_name = arg[1];
            }
            have_command = true;
        } else {
            if (!input)
                input = arg;
            else if (!output)
                output = arg;
            else
                failure("too many arguments, expected at most 2: input and output");
        }
    }

    struct Command_Arguments arguments = { .input = input, .output = output };
    for (uint d = 0; d < ARRAY_SIZE(command_definitions); ++d) {
        struct Command_Definition* definition = &command_definitions[d];

        if (definition->is_default || (command_name && strcmp(definition->name, command_name) == 0)
            || (short_command_name && definition->short_name == short_command_name)) {
            switch (definition->function(&arguments)) {
            case COMMAND_OK:
                return EXIT_SUCCESS;
            case COMMAND_FAIL:
                return EXIT_FAILURE;
            }
        }
    }
}