/*  Copyright (C) 2022 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <histedit.h>

#include "knot/common/log.h"
#include "utils/common/lookup.h"
#include "utils/knotc/interactive.h"
#include "utils/knotc/commands.h"
#include "contrib/openbsd/strlcat.h"
#include "contrib/string.h"

#define PROGRAM_NAME	"knotc"
#define HISTORY_FILE	".knotc_history"

extern params_t params;

typedef struct {
	const char **args;
	int count;
	bool dname;
} dup_check_ctx_t;

static void cmds_lookup(EditLine *el, const char *str, size_t str_len)
{
	lookup_t lookup;
	int ret = lookup_init(&lookup);
	if (ret != KNOT_EOK) {
		return;
	}

	// Fill the lookup with command names.
	for (const cmd_desc_t *desc = cmd_table; desc->name != NULL; desc++) {
		ret = lookup_insert(&lookup, desc->name, NULL);
		if (ret != KNOT_EOK) {
			goto cmds_lookup_finish;
		}
	}

	(void)lookup_complete(&lookup, str, str_len, el, true);

cmds_lookup_finish:
	lookup_deinit(&lookup);
}

static void remove_duplicates(lookup_t *lookup, dup_check_ctx_t *check_ctx)
{
	if (check_ctx == NULL) {
		return;
	}

	knot_dname_txt_storage_t dname = "";
	for (int i = 0; i < check_ctx->count; i++) {
		const char *arg = (check_ctx->args)[i];
		size_t len = strlen(arg);
		if (check_ctx->dname && len > 1 && arg[len - 1] != '.') {
			strlcat(dname, arg, sizeof(dname));
			strlcat(dname, ".", sizeof(dname));
			arg = dname;
		}
		(void)lookup_remove(lookup, arg);
	}
}

static void local_zones_lookup(EditLine *el, const char *str, size_t str_len,
                               dup_check_ctx_t *check_ctx)
{
	lookup_t lookup;
	int ret = lookup_init(&lookup);
	if (ret != KNOT_EOK) {
		return;
	}

	knot_dname_txt_storage_t buff;

	// Fill the lookup with local zone names.
	for (conf_iter_t iter = conf_iter(conf(), C_ZONE);
	     iter.code == KNOT_EOK; conf_iter_next(conf(), &iter)) {
		conf_val_t val = conf_iter_id(conf(), &iter);
		char *name = knot_dname_to_str(buff, conf_dname(&val), sizeof(buff));

		ret = lookup_insert(&lookup, name, NULL);
		if (ret != KNOT_EOK) {
			conf_iter_finish(conf(), &iter);
			goto local_zones_lookup_finish;
		}
	}

	remove_duplicates(&lookup, check_ctx);
	(void)lookup_complete(&lookup, str, str_len, el, true);

local_zones_lookup_finish:
	lookup_deinit(&lookup);
}

static void list_separators(EditLine *el, const char *separators)
{
	lookup_t lookup;
	if (lookup_init(&lookup) != KNOT_EOK) {
		return;
	}

	size_t count = strlen(separators);
	for (int i = 0; i < count; i++) {
		char sep[2] = { separators[i] };
		(void)lookup_insert(&lookup, sep, NULL);
	}
	(void)lookup_complete(&lookup, "", 0, el, false);

	lookup_deinit(&lookup);
}

static bool rmt_lookup(EditLine *el, const char *str, size_t str_len,
                       const char *section, const char *item, const char *id,
                       dup_check_ctx_t *check_ctx, bool add_space, const char *flags,
                       knot_ctl_idx_t idx)
{
	const cmd_desc_t *desc = cmd_table;
	while (desc->name != NULL && desc->cmd != CTL_CONF_LIST) {
		desc++;
	}
	assert(desc->name != NULL);

	knot_ctl_data_t query = {
		[KNOT_CTL_IDX_CMD] = ctl_cmd_to_str(desc->cmd),
		[KNOT_CTL_IDX_SECTION] = section,
		[KNOT_CTL_IDX_ITEM] = item,
		[KNOT_CTL_IDX_ID] = id,
		[KNOT_CTL_IDX_FLAGS] = flags
	};

	lookup_t lookup;
	knot_ctl_t *ctl = NULL;
	bool found = false;

	if (set_ctl(&ctl, params.socket, DEFAULT_CTL_TIMEOUT_MS, desc) != KNOT_EOK ||
	    knot_ctl_send(ctl, KNOT_CTL_TYPE_DATA, &query) != KNOT_EOK ||
	    knot_ctl_send(ctl, KNOT_CTL_TYPE_BLOCK, NULL) != KNOT_EOK ||
	    lookup_init(&lookup) != KNOT_EOK) {
		unset_ctl(ctl);
		return found;
	}

	while (true) {
		knot_ctl_type_t type;
		knot_ctl_data_t reply;

		if (knot_ctl_receive(ctl, &type, &reply) != KNOT_EOK) {
			goto rmt_lookup_finish;
		}

		if (type != KNOT_CTL_TYPE_DATA && type != KNOT_CTL_TYPE_EXTRA) {
			break;
		}

		const char *error = reply[KNOT_CTL_IDX_ERROR];
		if (error != NULL) {
			printf("\nnotice: (%s)\n", error);
			goto rmt_lookup_finish;
		}

		// Insert the received name into the lookup.
		if (lookup_insert(&lookup, reply[idx], NULL) != KNOT_EOK) {
			goto rmt_lookup_finish;
		}
	}

	remove_duplicates(&lookup, check_ctx);
	if (lookup_complete(&lookup, str, str_len, el, add_space) == KNOT_EOK &&
	    str != NULL && strcmp(lookup.found.key, str) == 0) {
		found = true;
	}

rmt_lookup_finish:
	lookup_deinit(&lookup);
	unset_ctl(ctl);

	return found;
}

static bool id_lookup(EditLine *el, const char *str, size_t str_len,
                      const char *section, const cmd_desc_t *cmd_desc,
                      dup_check_ctx_t *ctx, bool add_space, bool zones)
{
	char flags[4] = "";
	if (zones) {
		strlcat(flags, CTL_FLAG_LIST_ZONES, sizeof(flags));
	} else if (cmd_desc->flags & CMD_FREQ_TXN) {
		strlcat(flags, CTL_FLAG_LIST_TXN, sizeof(flags));
	}

	return rmt_lookup(el, str, str_len, section, NULL, NULL, ctx, add_space,
	                  flags, KNOT_CTL_IDX_ID);
}

static void val_lookup(EditLine *el, const char *str, size_t str_len,
                       const char *section, const char *item, const char *id,
                       dup_check_ctx_t *ctx, bool list_schema)
{
	char flags[4] = CTL_FLAG_LIST_TXN;
	if (list_schema) {
		strlcat(flags, CTL_FLAG_LIST_SCHEMA, sizeof(flags));
	}

	(void)rmt_lookup(el, str, str_len, section, item, id, ctx, true,
	                 flags, KNOT_CTL_IDX_DATA);
}

static bool list_lookup(EditLine *el, const char *str, const char *section)
{
	const char *flags = CTL_FLAG_LIST_SCHEMA;
	knot_ctl_idx_t idx = (section == NULL) ? KNOT_CTL_IDX_SECTION : KNOT_CTL_IDX_ITEM;

	return rmt_lookup(el, str, strlen(str), section, NULL, NULL, NULL,
	                  section != NULL, flags, idx);
}

static void item_lookup(EditLine *el, const char *str, const cmd_desc_t *cmd_desc)
{
	// List all sections.
	if (str == NULL) {
		(void)list_lookup(el, "", NULL);
		return;
	}

	// Check for id specification.
	char *id = (strchr(str, '['));
	if (id != NULL) {
		char *section = strndup(str, id - str);

		// Check for completed id specification.
		char *id_stop = (strchr(id, ']'));
		if (id_stop != NULL) {
			// Complete the item name.
			if (*(id_stop + 1) == '.') {
				(void)list_lookup(el, id_stop + 2, section);
			} else {
				list_separators(el, ".");
			}
		} else {
			// Complete the section id.
			if (id_lookup(el, id + 1, strlen(id + 1), section, cmd_desc,
			              NULL, false, false)) {
				list_separators(el, "]");
			}
		}

		free(section);
	} else {
		// Check for item specification.
		char *dot = (strchr(str, '.'));
		if (dot != NULL) {
			// Complete the item name.
			char *section = strndup(str, dot - str);
			(void)list_lookup(el, dot + 1, section);
			free(section);
		} else {
			// Complete the section name.
			if (list_lookup(el, str, NULL)) {
				list_separators(el, "[.");
			}
		}
	}
}

static unsigned char complete(EditLine *el, int ch)
{
	int argc, token, pos;
	const char **argv;

	const LineInfo *li = el_line(el);
	Tokenizer *tok = tok_init(NULL);

	// Parse the line.
	int ret = tok_line(tok, li, &argc, &argv, &token, &pos);
	if (ret != 0) {
		goto complete_exit;
	}

	// Show possible commands.
	if (argc == 0) {
		print_commands();
		goto complete_exit;
	}

	// Complete the command name.
	if (token == 0) {
		cmds_lookup(el, argv[0], pos);
		goto complete_exit;
	}

	// Find the command descriptor.
	const cmd_desc_t *desc = cmd_table;
	while (desc->name != NULL && strcmp(desc->name, argv[0]) != 0) {
		desc++;
	}
	if (desc->name == NULL) {
		goto complete_exit;
	}

	// Finish if a command with no or unsupported arguments.
	if (desc->flags == CMD_FNONE || desc->flags == CMD_FREAD ||
	    desc->flags == CMD_FWRITE) {
		goto complete_exit;
	}

	ret = set_config(desc, &params);
	if (ret != KNOT_EOK) {
		goto complete_exit;
	}

	// Complete the zone name.
	if (desc->flags & (CMD_FREQ_ZONE | CMD_FOPT_ZONE)) {
		if (token > 1 && !(desc->flags & CMD_FOPT_ZONE)) {
			goto complete_exit;
		}

		dup_check_ctx_t ctx = { &argv[1], token - 1, true };
		if (desc->flags & CMD_FREAD) {
			local_zones_lookup(el, argv[token], pos, &ctx);
		} else {
			id_lookup(el, argv[token], pos, "zone", desc, &ctx, true, true);
		}
		goto complete_exit;
	// Complete the section/id/item name or item value.
	} else if (desc->flags & (CMD_FOPT_ITEM | CMD_FREQ_ITEM)) {
		if (token == 1) {
			item_lookup(el, argv[1], desc);
		} else if (desc->flags & CMD_FOPT_DATA) {
			char section[YP_MAX_TXT_KEY_LEN + 1] = "";
			char item[YP_MAX_TXT_KEY_LEN + 1] = "";
			char id[KNOT_DNAME_TXT_MAXLEN + 1] = "";

			assert(YP_MAX_TXT_KEY_LEN == 127);
			assert(KNOT_DNAME_TXT_MAXLEN == 1004);
			if (sscanf(argv[1], "%127[^[][%1004[^]]].%127s", section, id, item) == 3 ||
			    sscanf(argv[1], "%127[^.].%127s", section, item) == 2) {
				dup_check_ctx_t ctx = { &argv[2], token - 2 };
				val_lookup(el, argv[token], pos, section, item, id,
				           &ctx, desc->flags & CMD_FLIST_SCHEMA);
			}
		}
		goto complete_exit;
	}

complete_exit:
	conf_update(NULL, CONF_UPD_FNONE);
	tok_reset(tok);
	tok_end(tok);

	return CC_REDISPLAY;
}

static char *prompt(EditLine *el)
{
	return PROGRAM_NAME"> ";
}

int interactive_loop(params_t *process_params)
{
	char *hist_file = NULL;
	const char *home = getenv("HOME");
	if (home != NULL) {
		hist_file = sprintf_alloc("%s/%s", home, HISTORY_FILE);
	}
	if (hist_file == NULL) {
		log_notice("failed to get home directory");
	}

	EditLine *el = el_init(PROGRAM_NAME, stdin, stdout, stderr);
	if (el == NULL) {
		log_error("interactive mode not available");
		free(hist_file);
		return KNOT_ERROR;
	}

	History *hist = history_init();
	if (hist == NULL) {
		log_error("interactive mode not available");
		el_end(el);
		free(hist_file);
		return KNOT_ERROR;
	}

	HistEvent hev = { 0 };
	history(hist, &hev, H_SETSIZE, 1000);
	history(hist, &hev, H_SETUNIQUE, 1);
	el_set(el, EL_HIST, history, hist);
	history(hist, &hev, H_LOAD, hist_file);

	el_set(el, EL_TERMINAL, NULL);
	el_set(el, EL_EDITOR, "emacs");
	el_set(el, EL_PROMPT, prompt);
	el_set(el, EL_SIGNAL, 1);
	el_source(el, NULL);

	// Warning: these two el_sets()'s always leak -- in libedit2 library!
	// For more details see this commit's message.
	el_set(el, EL_ADDFN, PROGRAM_NAME"-complete",
	       "Perform "PROGRAM_NAME" completion.", complete);
	el_set(el, EL_BIND, "^I",  PROGRAM_NAME"-complete", NULL);

	int count;
	const char *line;
	while ((line = el_gets(el, &count)) != NULL && count > 0) {
		Tokenizer *tok = tok_init(NULL);

		// Tokenize the current line.
		int argc;
		const char **argv;
		const LineInfo *li = el_line(el);
		int ret = tok_line(tok, li, &argc, &argv, NULL, NULL);
		if (ret == 0 && argc != 0) {
			history(hist, &hev, H_ENTER, line);
			history(hist, &hev, H_SAVE, hist_file);

			// Process the command.
			ret = process_cmd(argc, argv, process_params);
		}

		tok_reset(tok);
		tok_end(tok);

		// Check for the exit command.
		if (ret == KNOT_CTL_ESTOP) {
			break;
		}
	}

	history_end(hist);
	free(hist_file);

	el_end(el);

	return KNOT_EOK;
}