#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include "ucore/string.h"
#include "ucore/strvec.h"
#include "ucore/utils.h"
#include "ucore/backtrace.h"
//
enum UCCmdRc {
    UC_CMDRC_OK,  
    /**Executed with warning */
    UC_CMDRC_WARNING,
    /*incomplete command */
    UC_CMDRC_INCOMPLETE,
    /*Command cann't uniquely be distinguished */
    UC_CMDRC_AMBIGUOUS,
    /* Command doesn't exist*/
    UC_CMDRC_NOT_FOUND,
    /*Not executed, generic error */
    UC_CMDRC_ERROR,
};

struct UCCmdArgs;
typedef enum UCCmdRc (*UCCmdHandler)(const struct UCCmdArgs *args);

enum UCCmdType {
    UC_CMD_ROOT = 1,
    UC_CMD_KEYWORD,
    UC_CMD_LIST,
    UC_CMD_STRING,
    UC_CMD_END,
};

struct UCCmdWord {
    char *word;
    char *descr;
};

struct UCCmdList {
    struct UCStrv words;
    struct UCStrv descrs;
};

/**
 * Command are broken into words and inserted into a tree.
 * the 3 commands:
 *   show all
 *   date
 *   show all bottles
 * Results in the tree:
 *
 *  +--------+ child  +--------+ child  +-------+ child +-----+
 *  |  root  |------->|  show  |------->|  all  |------>| END |
 *  +--------+        +--------+        +-------+       +-----+
 *                       | next                           | next
 *                       V                                V 
 *                    +--------+ child +-----+         +--------+ child +-----+
 *                    |  date  |-----> | END |         | bottles|------>| END |
 *                    +--------+       +-----+         +--------+       +-----+
 *                                                                 
 * END nodes are complete commands. Other child/next pointers will be nULL
 */
struct UCCmdNode {
    enum UCCmdType type;
    union {
        struct UCCmdWord word;
        struct UCCmdList list;
        struct UCCmdDef *cmd;
    } data;
    uint32_t flags;
    struct UCCmdNode *next; //next at same level
    struct UCCmdNode *child;
};

struct UCCmdRunner {
    struct UCCmdNode *root_node;
    struct UCCmdNode _root;
};

struct UCCmdDef {
    const char *cmd;
    const char *help;
    UCCmdHandler callback;
    uint32_t flags;
};


//max words in a single command
#define UC_CMD_MAX_WORDS 32

struct UCCmdTokenizer {
    char *cmd_copy;
    char *cmd_words[UC_CMD_MAX_WORDS];
    int num_words;
};

struct UCCmdArgs {
    struct UCStrv argv;
    struct UCCmdDef *cmd;
};

void print_args(const struct UCStrv *args);
static int uc_cmd_type_is_variable(enum UCCmdType type)
{
    return type == UC_CMD_LIST ||
           type == UC_CMD_STRING;
}

static void uc_cmd_tokenize(struct UCCmdTokenizer *t, const char *cmd, const char *delim)
{
    
    t->num_words = 0;
    t->cmd_copy = strdup(cmd);
    if (t->cmd_copy == NULL) {
        assert(t->cmd_copy);
        return;
    }

    if (delim == NULL) {
        delim = "\r\n\t\v ";
    }

    t->num_words = getfields(t->cmd_copy, 
                             t->cmd_words, 
                             ARRAY_SIZE(t->cmd_words), 
                             1, 
                             delim);
}

static void
uc_cmd_tokenize_destroy(struct UCCmdTokenizer *t)

{
    free(t->cmd_copy);
    t->num_words = 0;
    t->cmd_copy = NULL;
}

void
uc_cmd_runner_init(struct UCCmdRunner *r)
{
    memset(r, 0, sizeof *r);
    r->root_node = &r->_root;
    r->_root.type = UC_CMD_KEYWORD;
}

void
uc_cmd_node_dealloc(struct UCCmdNode *n)
{
    struct UCCmdNode *next;
    while (n) {
        uc_cmd_node_dealloc(n->child); 
        next = n->next;
        if (n->type == UC_CMD_KEYWORD) {
            free(n->data.word.word);
            free(n->data.word.descr);
        } else if (n->type == UC_CMD_LIST) {
            uc_strv_destroy(&n->data.list.words);
            uc_strv_destroy(&n->data.list.descrs);
        } else if (n->type == UC_CMD_STRING) {
            free(n->data.word.word);
            free(n->data.word.descr);
        }
        free(n);
        n = next;
    }
}

void
uc_cmd_runner_destroy(struct UCCmdRunner *r)
{
    uc_cmd_node_dealloc(r->root_node->child);
    r->root_node->child = NULL;
}

static struct UCCmdNode *
uc_cmd_node_alloc(enum UCCmdType type, uint32_t flags)
{
    struct UCCmdNode *n;

    n = calloc(1, sizeof *n);
    if (n == NULL) {
        return NULL;
    }

    n->type = type;
    n->flags = flags;

    return n;
}

static struct UCCmdNode *
uc_cmd_node_create(const char *word)
{
    struct UCCmdNode *node = NULL;

    if (word[0] == '(') { //list (foo|bar|baz)
        struct UCCmdTokenizer t;

        uc_cmd_tokenize(&t, word, "() |\t\v");
        if (t.num_words > 0) {
            node = uc_cmd_node_alloc(UC_CMD_LIST, 0);

            uc_strv_init(&node->data.list.words);
            uc_strv_init(&node->data.list.descrs);

            for (int i = 0 ; i < t.num_words;  i++) {
               uc_strv_append(&node->data.list.words, t.cmd_words[i]);
            }
        }

        uc_cmd_tokenize_destroy(&t);
    } else if (isupper(word[0])) { 
        node = uc_cmd_node_alloc(UC_CMD_STRING, 0);
        node->data.word.word = strdup(word);
    } else {
        node = uc_cmd_node_alloc(UC_CMD_KEYWORD, 0);
        node->data.word.word = strdup(word);
    }

    return node;
}

static int 
uc_cmd_node_match(const struct UCCmdNode *n, const char *word, struct UCStrv *args)
{
    size_t word_len;
    int found = 0;

    if (word == NULL || word[0] == 0) {
        return 0;
    }

    word_len = strlen(word);

    if (n->type == UC_CMD_KEYWORD) {

        if (strncmp(word, n->data.word.word, word_len) == 0) {
            if (args != NULL) {
                uc_strv_append(args, n->data.word.word);
            }
            found = 1;
        }
    } else if (n->type == UC_CMD_LIST) {
        const struct UCStrv *v = &n->data.list.words;

        assert(v);

        for(size_t i = 0; i < v->cnt; i++) {

            if (strncmp(word, v->strings[i], word_len) == 0) {
                if (args != NULL) {
                    uc_strv_append(args, v->strings[i]);
                }
                found = 1;
            }
        }
    } else if (n->type == UC_CMD_STRING) {
        if (args != NULL) {
            uc_strv_append(args, word);
        }
        found = 1;
    }

    return found;

}

static struct UCCmdNode *
uc_cmd_add(struct UCCmdNode *parent, const char *word)
{
    struct UCCmdNode *new_node;
    struct UCCmdNode **iter = &parent->child;

    assert(parent);

    new_node = uc_cmd_node_create(word);
    if (new_node == NULL) {
        return NULL;
    }

    while (*iter) {
        struct UCCmdNode *n = *iter;

        if (uc_cmd_type_is_variable(new_node->type) && n->type != UC_CMD_END) {
            //we don't support combinations of keywords and variables
            //at the same level.
            uc_cmd_node_dealloc(new_node);
            return NULL;
        }
        //TODO check for ambiguous word (e.g. add "short" when "shorter" already exists)
        if (new_node->type == UC_CMD_KEYWORD && uc_cmd_node_match(n, word, NULL)) {
            uc_cmd_node_dealloc(new_node);
            return *iter;
        }
        iter = &n->next;
    }
   
   *iter = new_node;

   return new_node;
}

int
uc_cmd_install_noassert(struct UCCmdRunner *r, struct UCCmdDef *cmd)
{
    struct UCCmdNode *node = r->root_node;
    struct UCCmdNode *new_node; 
    struct UCCmdTokenizer t;

    uc_cmd_tokenize(&t, cmd->cmd, NULL);
    if (t.num_words <= 0) {
        uc_cmd_tokenize_destroy(&t);
        return -1;
    }

    for (int i = 0; i < t.num_words; i++) {
        node = uc_cmd_add(node, t.cmd_words[i]);
        if (node == NULL) {
            uc_cmd_tokenize_destroy(&t);
            return -2;
        }
    }
    
    //TODO, check for duplicate command here.

    new_node = uc_cmd_node_alloc(UC_CMD_END, 0);
    if (new_node == NULL) {
        uc_cmd_tokenize_destroy(&t);
        return -1;
    }
    new_node->data.cmd = cmd;
    new_node->next = node->child;
    node->child = new_node;


    uc_cmd_tokenize_destroy(&t);

    return 0;
}

int
uc_cmd_install(struct UCCmdRunner *r, struct UCCmdDef *cmd)
{
    int rc;
    
    rc = uc_cmd_install_noassert(r, cmd);
    UC_ASSERT(rc == 0);

    return rc;
}

enum UCCmdRc
uc_cmd_find(struct UCCmdNode *first, 
            const struct UCCmdTokenizer *t, 
            struct UCStrv *args,
            struct UCCmdNode **result)
{
    struct UCCmdNode *node = first;
    enum UCCmdRc rc = UC_CMDRC_NOT_FOUND;

    for (int i = 0; i < t->num_words && node; i++) {
        int n_found = 0;
        struct UCCmdNode *found = NULL;

        while (node) {
            if (uc_cmd_node_match(node, t->cmd_words[i], args)) {
                if (n_found == 0) {
                    //keep the 1. matched
                    found = node;
                }
                n_found++;
            }
            node = node->next;
        }

        if (n_found == 1) {
            node = found->child;
            rc = UC_CMDRC_OK;
        } else if (n_found > 1) {
            node = found;
            rc = UC_CMDRC_AMBIGUOUS;
            break;
        }
    }

    *result = node;

    if (node == NULL) {
        rc = UC_CMDRC_NOT_FOUND;
    }

    return rc;
}


enum UCCmdRc
uc_cmd_parse_and_find(struct UCCmdRunner *r, const char *cmd_line,
                                   struct UCStrv *args,
                                   struct UCCmdNode **result)
{

    struct UCCmdNode *node = r->root_node->child;
    struct UCCmdTokenizer t;
    enum UCCmdRc rc = UC_CMDRC_ERROR;

    //make a copy since getfields destroys the original string
    uc_cmd_tokenize(&t, cmd_line, NULL);

    if (t.num_words > 0) {

        //match the commands towards the command tree
        //
        rc = uc_cmd_find(node, &t, args, result);
    }

    uc_cmd_tokenize_destroy(&t);

    return rc;
}

enum UCCmdRc
uc_cmd_complete(struct UCCmdRunner *r, const char *cmd_line)
{

    struct UCStrv completions = UC_STRV_INITIALIZER;

    struct UCCmdNode *found = NULL;
    enum UCCmdRc rc;

    rc = uc_cmd_parse_and_find(r, cmd_line, NULL, &found);
    if (rc != UC_CMDRC_NOT_FOUND && found != NULL) {
        struct UCCmdNode *node = found;
        while (node) {
            if (node->type == UC_CMD_END) {
                uc_strv_append(&completions, "<CR>");
            } else if (node->type == UC_CMD_LIST) {
                uc_strv_append_all(&completions, &node->data.list.words, 1);
            } else if (node->type == UC_CMD_STRING || 
                       node->type == UC_CMD_KEYWORD) {
                uc_strv_append(&completions, node->data.word.word);
            }
            node = node->next;
        }

        printf("Possible completions for '%s'\n", cmd_line);
        print_args(&completions);

    } else {
        printf("No possible completions\n");
    }

    uc_strv_destroy(&completions);
    
    return rc;
}


enum UCCmdRc
uc_cmd_run(struct UCCmdRunner *r, const char *cmd_line)
{
    struct UCCmdArgs args = {
        .argv = UC_STRV_INITIALIZER,
        .cmd  = NULL,
    };

    struct UCCmdNode *found = NULL;
    enum UCCmdRc rc;

    rc = uc_cmd_parse_and_find(r, cmd_line, &args.argv, &found);
    if (rc == UC_CMDRC_OK) {
        // Now check the current level for any UC_CMD_END
        // which indicates a complete command
        while (found) {
            if (found->type == UC_CMD_END) {
                break;
            }
            found = found->next;
        }

        if (found != NULL) {
            struct UCCmdDef *cmd = found->data.cmd;
            args.cmd = cmd;
            rc = cmd->callback(&args);
        } else {
            rc = UC_CMDRC_INCOMPLETE;
        }
    }
    
    uc_strv_destroy(&args.argv);

    return rc;
}


void print_args(const struct UCStrv *args)
{
    for (size_t i = 0; i < args->cnt; i++) {
        printf("arg %zu: '%s' ", i, args->strings[i]);
    }
    puts("");
}

enum UCCmdRc cmd1_cb(const struct UCCmdArgs *args)
{
    puts(__func__);
    print_args(&args->argv);

    return UC_CMDRC_OK;
}

enum UCCmdRc cmd2_cb(const struct UCCmdArgs *args)
{
    puts(__func__);
    print_args(&args->argv);

    return UC_CMDRC_OK;
}

enum UCCmdRc cmd3_cb(const struct UCCmdArgs *args)
{
    puts(__func__);
    print_args(&args->argv);

    return UC_CMDRC_OK;
}

enum UCCmdRc cmd4_cb(const struct UCCmdArgs *args)
{
    puts(__func__);
    print_args(&args->argv);

    return UC_CMDRC_OK;
}





int main(int argc, char *argv[])
{
    char line[128];
    struct UCCmdRunner r;
    struct UCCmdDef cmd1 = {
        "show all",
        "\n\n",
        cmd1_cb, 
        0,
        NULL
    };

    struct UCCmdDef cmd2 = {
        "show empty",
        "\n\n",
        cmd2_cb, 
        0,
        NULL
    };

    struct UCCmdDef cmd3 = {
        "show empty bottle",
        "\n\n\n",
        cmd3_cb, 
        0,
        NULL
    };

    struct UCCmdDef cmd4 = {
        "delete file NAME",
        "\n\nName of the file\n",
        cmd4_cb, 
        0,
        NULL
    };

    uc_cmd_runner_init(&r);
    uc_cmd_install(&r, &cmd1);
    uc_cmd_install(&r, &cmd2);
    uc_cmd_install(&r, &cmd3);
    uc_cmd_install(&r, &cmd4);

    uc_cmd_run(&r, "delete file /tmp/a");
    uc_cmd_run(&r, "show all");
    uc_cmd_run(&r, "show empty");
    uc_cmd_run(&r, "sh emp b");
    uc_cmd_run(&r, "");
    /*
    while (fgets(line,sizeof line, stdin)) {
        enum UCCmdRc rc = uc_cmd_run(&r, line);
        if (rc != UC_CMDRC_OK) {
            printf("Command failed with code %d\n", rc);
        }
    }
    */

    uc_cmd_complete(&r, "sho em");
    uc_cmd_complete(&r, "show  ");
    uc_cmd_complete(&r, "");
    uc_cmd_runner_destroy(&r);


    return 1;
}