#define _POSIX_C_SOURCE 200809L

#include "minimake.h"

#include <ctype.h>
#include <err.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#include "files/files.h"
#include "hash_maps/hash_maps.h"
#include "lines/lines.h"
#include "lists/lists.h"

// Static variables

static char *program_name;

static struct hash_map *variables = NULL;
static struct hash_map *rules = NULL;

// Keeps track of variables and rules order
static struct list *variables_list = NULL;
static struct list *rules_list = NULL;

// ==== Misc ====

static void hashmap_deep_free(struct hash_map *hash_map)
{
    if (hash_map == NULL)
        return;
    if (hash_map->data == NULL)
        return;

    for (size_t i = 0; i < hash_map->size; i++)
    {
        struct pair_list *entry = hash_map->data[i];
        while (entry != NULL)
        {
            struct pair_list *next = entry->next;
            // Ok c moche mais eh, ça fonctionne
            if (hash_map == rules)
            {
                struct rule *r = entry->value;
                free(r->name);
                list_deep_destroy(r->dependencies);
                list_deep_destroy(r->recipe);
                free(r);
            }
            else if (hash_map == variables)
            {
                // printf("Att to free: %s\n", entry->key);
                free(entry->key);
                free(entry->value);
            }
            else
            {
                printf("DEBUG: attempting to free a generic hashmap\n");
                free(entry->key);
                free(entry->value);
            }

            free(entry);
            entry = next;
        }
    }
    free(hash_map->data);
    free(hash_map);
}

static void free_all(void)
{
    list_destroy(rules_list);
    list_destroy(variables_list);
    hashmap_deep_free(rules);
    hashmap_deep_free(variables);
}

// ==== Parsing ====

// Registers a new rule in the hashmap
// WARNING Allocates memory on the heap,
// the rules hashmap should be freed before exit
static void register_rule(char *name, struct list *dependencies,
                          struct list *recipe)
{
    struct rule *rule = malloc(sizeof(struct rule));
    rule->name = name;
    rule->dependencies = dependencies;
    rule->recipe = recipe;

    int err = hashmap_insert(rules, name, rule, NULL);
    if (!err)
    {
        drop(GENERIC_ERR,
             "Internal Error: Couln't add entry for '%s' in the hashmap", name);
    }

    rules_list = list_append(rules_list, name);
}

// Registers a new variable in the hashmap
// WARNING Allocates memory on the heap,
// the variables hashmap should be freed before exit
static void register_variable(char *name, char *value)
{
    int err = hashmap_insert(variables, name, value, NULL);
    if (!err)
    {
        drop(GENERIC_ERR,
             "Internal Error: Couln't add entry for '%s' in the hashmap", name);
    }

    variables_list = list_append(variables_list, name);
}

// Parse dependencies from buf and returns them inside a chained list
static struct list *read_deps(struct line *l, size_t offset)
{
    size_t i = offset;
    size_t buf_size = l->length;
    char *buf = l->buffer;
    struct list *res = NULL;

    while (i < buf_size)
    {
        i += skipblanks(buf + i, buf_size - i);

        // Read word
        char *dep_name;
        i += readword(buf + i, buf_size - i, &dep_name);
        if (dep_name != NULL)
            // Add to list
            res = list_append(res, dep_name);

        // Comments
        if (buf[i] == '#')
            return res;

        // Unknown chars
        if (!ischar(buf[i]) && !isblank(buf[i]) && buf[i] != '\0'
            && buf[i] != '\n')
        {
            drop(GENERIC_ERR,
                 "Unexpected character '%c' after rule declaration at %lu:%lu",
                 buf[i], l->number, i);
        }
    }

    return res;
}

// Searches the following lines for recipes and returns them in the form of a
// list
// WARNING begins to read the following line
static struct list *read_recipe(struct line *l)
{
    FILE *stream = l->file_stream;
    char *buf = l->buffer;
    size_t buf_size = BUFFER_SIZE;

    struct list *res = NULL;

    // Getline
    while ((l->length = getline(&buf, &buf_size, stream)) != -1)
    {
        l->number++;

        // Skip blank lines and comments
        if (isblankline(l))
            continue;
        else if (buf[0] != '\t') // Not a recipe
        {
            l->buffer = buf; // Update buffer !
            return res;
        }
        else // Add recipe to list
        {
            size_t offset = 1 + skipblanks(buf + 1, l->length - 1);

            char *command = strdup(buf + offset);
            if (command == NULL)
            {
                drop(GENERIC_ERR,
                     "Internal error: couldn't duplicate string (%lu:1)",
                     l->number);
            }

            command[l->length - offset - 1] = '\0';
            res = list_append(res, command);
        }
    }

    l->buffer = buf;
    return res;
}

// === Variable Expansion ===

// Reads the value after a variable declaration
static char *read_variable_value(char *buf, size_t buf_len)
{
    size_t i = 0;
    size_t str_buf_size = STRING_BUFFER_SIZE;
    char *str_buf = malloc(sizeof(char) * str_buf_size);

    while (i < buf_len && buf[i] != '\n' && buf[i] != '#' && buf[i] != '\0')
    {
        // Reallocate more space if necessary
        if (i >= str_buf_size - 1)
        {
            str_buf_size += STRING_BUFFER_SIZE;
            str_buf = realloc(str_buf, str_buf_size);
            if (str_buf == NULL)
                drop(GENERIC_ERR, "Could not realloc");
        }

        str_buf[i] = buf[i];
        i++;
    }

    str_buf[i] = '\0';

    return str_buf;
}

// Reads variable name from buf until ')' and stores it into *result
// Returns its length on success and -1 on fail
// WARNING allocates memory on the heap, free *result after use
static size_t read_variable_name(struct line *line, size_t index, char **result)
{
    size_t i = index;
    char *buf = line->buffer;

    // Alloc var_buf
    size_t var_buf_size = STRING_BUFFER_SIZE;
    char *var_buf = malloc(sizeof(char) * var_buf_size);
    if (var_buf == NULL)
        drop(GENERIC_ERR, "Could not allocate more memory");

    size_t var_i = 0;
    while (buf[i] != '\n' && buf[i] != '\0' && buf[i] != '#' && buf[i] != ')')
    {
        // Reallocate more space if necessary
        var_buf_size = resize_buf(&var_buf, var_buf_size, i);

        // Copy
        var_buf[var_i] = buf[i];
        i++;
        var_i++;
    }
    var_buf[var_i] = '\0';

    // Mismatched parenthesis
    if (buf[i] != ')')
    {
        free(var_buf);
        *result = NULL;
        return 0;
    }

    i += 2;
    *result = var_buf;
    return i - index;
}

// Searches for variable in database and returns its value
// if no value is found, it drops an error and exit the program
// WARNING variable must be allocated on the heap as this function may attempt
//         to free it
// NOTE Takes line_number to print an helpful error message
static char *get_variable_value(char *variable_name, size_t line_number)
{
    char *value = hashmap_get(variables, variable_name);
    if (value == NULL)
    {
        // Adds tmp_buf to the list of items to free
        variables_list = list_append(variables_list, variable_name);
        drop(GENERIC_ERR, "Could not find specified variable '%s' at line %lu",
             variable_name, line_number);
    }

    free(variable_name);
    return value;
}

// Gets the corresponding value of the variable and stores it in *value
// Returns the number of skipped characters
size_t expand_variable(struct line *line, size_t index, char **value)
{
    size_t i = index;
    char *buf = line->buffer;

    // Name in parenthesis
    if (buf[i] == '(')
    {
        // Read variable
        char *var_name;
        i++;
        i += read_variable_name(line, i, &var_name);
        if (var_name == NULL)
            drop(GENERIC_ERR, "Mismatched parenthesis at %lu:%lu", i,
                 line->number);

        // Get corresponding value
        *value = get_variable_value(var_name, line->number);

        // Return
        return i - index;
    }
    else // Single char variable
    {
        // '$ '
        if (isblank(buf[i]) || isspace(buf[i]))
            drop(2, "Unauthorized character '%c' at %lu:%lu", buf[i],
                 line->number, i);
        else
        {
            // Allocate temporary buffer to hold variable name
            char *var_name = malloc(2 * sizeof(char));
            if (var_name == NULL)
                // Seriously, not even two bytes
                drop(GENERIC_ERR, "Could not allocate memory");

            var_name[0] = buf[i];
            var_name[1] = '\0';

            // Escape '$$'
            if (buf[i] == '$')
            {
                *value = var_name;
                return 2;
            }

            // Get corresponding value
            *value = get_variable_value(var_name, line->number);
            free(var_name);
        }

        return 2;
    }
}

// =================

// Takes a buffer containing the line to parse and it length
// As well as the line number in the file for error handling
static void parse_line(struct line *current_line)
{
    char *buf = current_line->buffer;
    size_t line_size = current_line->length;

    size_t i = 0;

    i += skipblanks(buf + i, line_size - i);

    // Read name
    char *name;
    // i += readword(buf + i, line_size - i, &name);
    i += read_declaration(current_line, i, &name);
    // if (name == NULL)
    //     errx(1, "Il s'est passé quoi là ? \nUnexpected character at %lu:%lu",
    //          current_line->number, i);

    i += skipblanks(buf + i, line_size - i);

    // Potential elements
    struct list *dependencies;
    struct list *recipe;
    char *value;

    // Definition type
    switch (buf[i])
    {
    // Variable
    case '=':
        i += skipblanks(buf + i + 1, line_size - i) + 1;
        value = read_variable_value(buf + i, line_size - i);
        register_variable(name, value);
        break;

    // Rule
    case ':':
        dependencies = read_deps(current_line, i + 1);
        recipe = read_recipe(current_line);
        register_rule(name, dependencies, recipe);

        // Check for EOF
        if (current_line->length == -1)
            return;

        parse_line(current_line);
        // TODO: check for loooooops

        break;

    // Blank line
    case '\0':
    case '#':
        if (name != NULL)
        {
            drop(GENERIC_ERR,
                 "Unexpected character '%c' after declaration '%s' at line %lu",
                 buf[i], name, current_line->number);
        }
        break;

    default:
        drop(GENERIC_ERR,
             "Unexpected character '%c' after declaration '%s' at line %lu",
             buf[i], name, current_line->number);
    }

    // free(name);
}

void make_parse(char *path)
{
    // Open file
    FILE *stream = fopen(path, "r");
    if (stream == 0)
        errx(2, "Could not open file: %s", path);

    // Init hash maps
    variables = hashmap_init(HASHMAP_SIZE);
    rules = hashmap_init(HASHMAP_SIZE);
    if (variables == NULL || rules == NULL)
        errx(1, "Internal error: Failed to initiate hash maps");

    // Allocate line buffer
    size_t buf_size = BUFFER_SIZE;
    char *buf = malloc(sizeof(char) * buf_size);
    if (buf == NULL)
        drop(GENERIC_ERR, "Could not allocate more memory");

    // Parse line by line
    ssize_t nread;
    struct line current_line;
    current_line.number = 1;
    current_line.file_stream = stream;
    while ((nread = getline(&buf, &buf_size, stream)) != -1)
    {
        if (nread == -1)
            drop(GENERIC_ERR, "Could not get line %lu", current_line.number);

        current_line.buffer = buf;
        current_line.length = nread;

        parse_line(&current_line);

        current_line.number += 1;
    }

    free(buf);
    fclose(stream);
    return;
}

// ==== Runtime ====

// Return 1 if rule is up to date, 0 otherwise
static int uptodate(struct rule *rule)
{
    struct stat path_stat;

    if (lstat(rule->name, &path_stat) != 0) // target doesn't exists
        return 0;

    struct list *dependencies = rule->dependencies;
    while (dependencies != NULL)
    {
        char *depname = dependencies->data;
        if (lstat(depname, &path_stat) != 0) // Dependecy doesn't exists
            return 0;
    }
    return 1;
}

// Expands and run a specified rule
static int run_rule(struct rule *rule)
{
    // Check if p to date
    if (uptodate(rule))
    {
        printf("%s: '%s' is up to date.", program_name, rule->name);
        return 0;
    }

    struct list *commands = rule->recipe;
    struct list *dependencies = rule->dependencies;

    // Build dependencies
    while (dependencies != NULL)
    {
        // Expand variable
        // TODO

        // Check file existence
        if (!file_exists(dependencies->data))
        {
            // Check rule existence instead
            struct rule *dep_rule = hashmap_get(rules, dependencies->data);
            if (dep_rule != NULL)
            {
                int res = run_rule(dep_rule);
                if (res != 0) // Exit on error
                    return res;
            }
            else
            {
                drop(GENERIC_ERR, "No rule to make target '%s'",
                     dependencies->data);
            }
        }

        dependencies = dependencies->next;
    }

    // Empty recipe
    if (commands == NULL)
    {
        printf("%s: Nothing to be done for '%s'.\n", program_name, rule->name);
        return 0;
    }

    while (commands != NULL)
    {
        // Expand command variables
        // TODO

        // Run
        int res = run_command(commands->data);
        if (res != 0) // Exit on error
            return res;

        commands = commands->next;
    }

    return 0;
}

// Run the given rules after parsing
int make_run(struct list *given_rules)
{
    if (given_rules == NULL)
    {
        // No rule specified => run first rule found in the Makefile
        if (rules_list == NULL)
            drop(GENERIC_ERR, "No targets");

        struct rule *full_rule = hashmap_get(rules, rules_list->data);
        if (full_rule == NULL)
            drop(GENERIC_ERR,
                 "Internal error: Could not retrieve target '%s' in database",
                 rules_list->data);

        return run_rule(full_rule);
    }
    else
    {
        while (given_rules != NULL)
        {
            struct rule *full_rule = hashmap_get(rules, given_rules->data);
            if (full_rule == NULL)
                drop(GENERIC_ERR, "No rule to make target '%s'",
                     given_rules->data);

            int res = run_rule(full_rule);
            if (res != 0)
                return res;

            given_rules = given_rules->next;
        }
        return 0;
    }
}

// ==== MAKE ====

int make(char *path, struct list *rules, char *exec_name, int flags)
{
    program_name = exec_name;

    make_parse(path);

    // Print
    if (flags & FLAGS_PRINT)
    {
        dump_database();
        free_all();
        return 0;
    }

    // Run
    int status = make_run(rules);
    free_all();
    return status;
}

// Prints an error message before exiting gracefully (by freeing all variables)
void drop(int status, char *format, ...)
{
    // Print
    va_list args;
    va_start(args, format);
    fprintf(stderr, "%s: *** ", program_name);
    vfprintf(stderr, format, args);
    fprintf(stderr, ".  Stop.\n");
    va_end(args);

    free_all();
    exit(status);
}

void dump_database(void)
{
    struct list *elt;

    // Dump variables
    elt = variables_list;
    puts("# variables");
    while (elt != NULL)
    {
        // Get var
        char *val = hashmap_get(variables, elt->data);
        if (val == NULL)
            drop(GENERIC_ERR, "Could not get variable '%s' in database",
                 elt->data);

        // Print
        char *key = elt->data;
        printf("'%s' = '%s'\n", key, val);

        elt = elt->next;
    }
    // Dump rules
    elt = rules_list;
    puts("# rules");
    while (elt != NULL)
    {
        // Get rule
        struct rule *rule = hashmap_get(rules, elt->data);
        if (rule == NULL)
            drop(GENERIC_ERR, "Could not get rule '%s' in database", elt->data);

        // Print name
        printf("(%s):", rule->name);

        // Print dependencies
        struct list *dep = rule->dependencies;
        while (dep != NULL)
        {
            char *dep_str = dep->data;
            printf(" [%s]", dep_str);
            dep = dep->next;
        }
        putchar('\n');

        // Print recipe
        struct list *rcp = rule->recipe;
        while (rcp != NULL)
        {
            char *rcp_str = rcp->data;
            printf("\t'%s'\n", rcp_str);
            rcp = rcp->next;
        }

        elt = elt->next;
    }
}