#include <assert.h>
#include <getopt.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "string_view.c"
#include "read_line.c"
#include "errors.c"
#include "lexer.c"
#include "objects.c"
#include "parser.c"
#include "environment.c"
#include "primitives.c"

//
// Utility macros.
//

#define MAKE_SYM(STR) make_symbol((StringView){(STR), sizeof(STR) - 1})
#define MAKE_ENV_VAR(ENV,STR,VAR) \
    (env_add_symbol((ENV), MAKE_SYM(STR), (VAR)))
#define MAKE_ENV_PROC(ENV,STR,FUN) \
    (env_add_symbol((ENV), MAKE_SYM(STR), make_procedure(FUN)))

void
init(void) {
    // Initialize singletons.
    obj_nil = alloc_object(OBJ_TYPE_NIL);
    obj_true = alloc_object(OBJ_TYPE_BOOL);
    obj_false = alloc_object(OBJ_TYPE_BOOL);
    obj_err = alloc_object(OBJ_TYPE_ERR);

    // Global environment.
    global_env = env_create(NULL);

    // Primitive symbols.
    MAKE_ENV_VAR(global_env, "else", obj_true);
    MAKE_ENV_VAR(global_env, "nil", obj_nil);

    // Primitive procedures.
    MAKE_ENV_PROC(global_env, "eval", proc_eval);
    MAKE_ENV_PROC(global_env, "quote", proc_quote);
    MAKE_ENV_PROC(global_env, "car", proc_car);
    MAKE_ENV_PROC(global_env, "cdr", proc_cdr);
    MAKE_ENV_PROC(global_env, "cons", proc_cons);
    MAKE_ENV_PROC(global_env, "list", proc_list);
    MAKE_ENV_PROC(global_env, "+", proc_sum);
    MAKE_ENV_PROC(global_env, "-", proc_sub);
    MAKE_ENV_PROC(global_env, "*", proc_mul);
    MAKE_ENV_PROC(global_env, "/", proc_div);
    MAKE_ENV_PROC(global_env, "%", proc_mod);
    MAKE_ENV_PROC(global_env, "print", proc_print);
    MAKE_ENV_PROC(global_env, "display", proc_display);
    MAKE_ENV_PROC(global_env, "newline", proc_newline);
    MAKE_ENV_PROC(global_env, "boolean?", proc_is_boolean);
    MAKE_ENV_PROC(global_env, "nil?", proc_is_nil);
    MAKE_ENV_PROC(global_env, "symbol?", proc_is_symbol);
    MAKE_ENV_PROC(global_env, "string?", proc_is_string);
    MAKE_ENV_PROC(global_env, "fixnum?", proc_is_fixnum);
    MAKE_ENV_PROC(global_env, "pair?", proc_is_pair);
    MAKE_ENV_PROC(global_env, "procedure?", proc_is_procedure);
    MAKE_ENV_PROC(global_env, "error?", proc_is_error);
    MAKE_ENV_PROC(global_env, "not", proc_not);
    MAKE_ENV_PROC(global_env, "and", proc_and);
    MAKE_ENV_PROC(global_env, "or", proc_or);
    MAKE_ENV_PROC(global_env, "if", proc_if);
    MAKE_ENV_PROC(global_env, "cond", proc_cond);
    MAKE_ENV_PROC(global_env, "<", proc_num_less_than);
    MAKE_ENV_PROC(global_env, "<=", proc_num_lesseq_than);
    MAKE_ENV_PROC(global_env, ">", proc_num_greater_than);
    MAKE_ENV_PROC(global_env, ">=", proc_num_greatereq_than);
    MAKE_ENV_PROC(global_env, "=", proc_num_equal);
    MAKE_ENV_PROC(global_env, "eq?", proc_equal);
    MAKE_ENV_PROC(global_env, "def", proc_define);
    MAKE_ENV_PROC(global_env, "set!", proc_set);
    MAKE_ENV_PROC(global_env, "lambda", proc_lambda);

    // Runtime procedures.
    MAKE_ENV_PROC(global_env, "supress-errors", proc_supress_errors);
}

void
process_source(const StringView *source) {
    Tokens tokens = tokenize(source);
    if (errors_n != 0) {
        if (tokens.buf != NULL) {
            free(tokens.buf);
        }
        return;
    }

    Visitor visitor = (Visitor){
        .tokens = tokens,
        .current = 0,
    };
    while (has_next_token(&visitor) && peek_token(&visitor).type != TOKEN_EOF) {
        Object *root = parse_tree(&visitor);
        if (root == obj_err || errors_n != 0) {
            free_objects(root);
            break;
        }

        // FIXME: Not freeing result or intermediate objects, can leak memory.
        Object *result = eval(global_env, root);
        if (result != obj_nil) {
            display(result);
            printf("\n");
        }
        free_objects(root);
    }

    if (tokens.buf != NULL) {
        free(tokens.buf);
    }
}

#define REPL_PROMPT "bdl> "

void
run_repl(void) {
    printf("BDL REPL (Press Ctrl-D or Ctrl-C to exit)\n");
    while (true) {
        printf(REPL_PROMPT);
        StringView sv = read_line();
        if (sv.start == NULL) {
            return;
        }
        process_source(&sv);

        // Check if there were any errors.
        if (errors_n != 0 && !supress_errors) {
            for (size_t i = 0; i < errors_n; i++) {
                Error err = errors[i];
                for (size_t j = 0; j < err.col + sizeof(REPL_PROMPT) - 2; j++) {
                    putchar(' ');
                }
                printf("|\n");
                for (size_t j = 0; j < err.col + sizeof(REPL_PROMPT) - 2; j++) {
                    putchar(' ');
                }
                printf("%s\n", error_msgs[err.value]);
            }
            errors_n = 0;
            continue;
        }
    }
}

void
run_file(char *file_name) {
    FILE *file = fopen(file_name, "r");
    if (!file) {
        fprintf(stderr, "error: couldn't open input file: %s\n", file_name);
        exit(EXIT_FAILURE);
    }

    // Read entire file into memory.
    fseek(file, 0, SEEK_END);
    size_t file_size = ftell(file);
    fseek(file, 0, SEEK_SET);

    char *source = malloc(file_size + 1);
    fread(source, 1, file_size, file);
    source[file_size] = 0;

    StringView sv = (StringView){
        .start = source,
        .n = file_size,
    };

    process_source(&sv);

    // Check if there were any errors.
    if (errors_n != 0 && !supress_errors) {
        for (size_t i = 0; i < errors_n; i++) {
            Error err = errors[i];
            fprintf(stderr, "%s", file_name);
            if (err.line != 0) {
                fprintf(stderr, ":%ld:%ld", err.line, err.col);
            }
            fprintf(stderr, ": %s\n", error_msgs[err.value]);
        }
        errors_n = 0;
    }

    free(source);
    fclose(file);
}

#define STDIN_BUF_CAP 16

void
run_stdin(void) {
    size_t buf_size = 0;
    size_t buf_cap = STDIN_BUF_CAP;
    char *source = malloc(buf_cap * sizeof(char));

    char c;
    while ((c = getchar()) != EOF) {
        if (buf_size == buf_cap) {
            buf_cap *= 2;
            source = realloc(source, buf_cap * sizeof(char));
        }
        source[buf_size] = c;
        buf_size++;
    }

    StringView sv = (StringView){
        .start = source,
        .n = buf_size,
    };

    process_source(&sv);

    // Check if there were any errors.
    if (errors_n != 0 && !supress_errors) {
        for (size_t i = 0; i < errors_n; i++) {
            Error err = errors[i];
            fprintf(stderr, "stdin");
            if (err.line != 0) {
                fprintf(stderr, ":%ld:%ld", err.line, err.col);
            }
            fprintf(stderr, ": %s\n", error_msgs[err.value]);
        }
        errors_n = 0;
    }

    free(source);
}

#ifndef BIN_NAME
#define BIN_NAME "bdl"
#endif

void
print_usage(void) {
    printf("Usage: %s [options] <filename filename ...>\n", BIN_NAME);
    printf("\n");
    printf("\t-i\tInteractive mode (REPL).\n");
    printf("\n");
}

int
main(int argc, char *argv[]) {
    init();

    int option;
    while ((option = getopt(argc, argv, "i")) != -1) {
        switch (option) {
            case 'i': {
                // Interactive mode.
                run_repl();
                return EXIT_SUCCESS;
            } break;
            default: {
                print_usage();
                return EXIT_FAILURE;
            } break;
        }
    }

    // Run from stdin.
    if (optind == argc) {
        run_stdin();
        return EXIT_SUCCESS;
    }

    // Run from file.
    while (optind < argc) {
        char *file_name = argv[optind];
        run_file(file_name);
        optind++;
    }

    return EXIT_SUCCESS;
}