/*
 * db.c - Parts database
 *
 * Copyright 2012 by Werner Almesberger
 *
 * 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 2 of the License, or
 * (at your option) any later version.
 */


#include <stdlib.h>
#include <stdio.h>
#include <glib.h>

#include "util.h"
#include "lang.h"
#include "chr.h"
#include "db.h"


static GTree *tree = NULL;


static gint comp(gconstpointer a, gconstpointer b)
{
	const struct part *pa = a;
	const struct part *pb = b;

	/*
	 * Just subtracting the pointers may produce values outside the
	 * range of gint values.
	 */
	return pa->domain == pb->domain ?
	    pa->name < pb->name ? -1 : pa->name > pb->name ? 1 : 0 :
	    pa->domain < pb->domain ? -1 : 1;
}


struct part *part_lookup(const char *domain, const char *name)
{
	struct part part = {
		.domain = domain,
		.name = name,
	};

	if (!tree)
		return NULL;
	return g_tree_lookup(tree, &part);
}


struct part *part_add(const char *domain, const char *name)
{
	struct part part = {
		.domain = domain,
		.name = name,
		.param = NULL,
		.stock = NULL,
	};
	struct part *p;

	if (!tree)
		tree = g_tree_new(comp);
	p = g_tree_lookup(tree, &part);
	if (!p) {
		p = alloc_type(struct part);
		*p = part;
		p->next = p->prev = p;
		g_tree_insert(tree, p, p);
	}
	return p;
}


void part_alias(struct part *a, struct part *b)
{
	struct part *tmp, *tmp2;

	tmp = a->next;
	a->next = b;
	b->prev->next = tmp;

	tmp2 = b->prev;
	b->prev = a;
	tmp->prev = tmp2;
}


static void convert_params(struct param **params,
    const struct field *f, struct param ***res)
{
	struct param **p, *prm;
	const struct selector *sel;
	const struct condition *cond;

	while (f) {
		for (p = params; *p; p = &(*p)->next)
			if ((*p)->u.name == f->name)
				break;
		if (!*p) {
			f = f->next;
			continue;
		}

		/* remove from list */
		prm = *p;
		*p = prm->next;

		/* convert parameter */
		prm->u.field = f;
		if (!evaluate(f->fmt, prm->value.u.s, &prm->value))
			yyerrorf("invalid value for %s", f->name);

		/* add to result list */
		**res = prm;
		*res = &prm->next;
		prm->next = NULL;

		/* process selections */
		for (sel = f->sel; sel; sel = sel->next) {
			for (cond = sel->cond; cond; cond = cond->next)
				if (compare(f->fmt, &prm->value, cond->relop,
				    &cond->value))
					break;
			if (cond) {
				convert_params(params, sel->act.fields, res);
				convert_params(params, sel->act.rules, res);
				break;
			}
		}
		if (!sel) {
			convert_params(params, f->any.fields, res);
			convert_params(params, f->any.rules, res);
		}

		f = f->next;
	}
}


void part_finalize(struct part *part, const struct action *act)
{
	struct param *param = part->param;
	struct param **res = &part->param;
	struct param *next;

	part->param = NULL;
	convert_params(&param, act->fields, &res);
	convert_params(&param, act->rules, &res);
	while (param) {
		yywarnf("extra parameter: %s", param->u.name);
		next = param->next;
		free(param);
		param = next;
	}
}


void part_add_stock(struct part *part, struct stock *s)
{
	if (!part->stock) {
		part->stock = s;
		return;
	}
	yyerrorf("part %s %s already has stock", part->domain, part->name);
}


/* ----- Dumping ----------------------------------------------------------- */


static void dump_stock(FILE *file, const struct stock *s)
{
	const struct price *p;

	fprintf(file, "    %s %s  %d %d  %s %g",
	    s->provider->name, s->cat, s->avail, s->package, s->curr->name,
	    s->add);
	for (p = s->price; p; p = p->next)
		fprintf(file,  " %d %g", p->qty, p->value);
	fprintf(file, "\n");
}


void part_dump(FILE *file, const struct part *part)
{
	const struct param *p;

	fprintf(file, "%s %s\n", part->domain, part->name);
	if (part->param) {
		fprintf(file, "   ");
		for (p = part->param; p; p = p->next) {
			fprintf(file, " %s=", p->u.field->name);
			dump_param(file, p->u.field->fmt, &p->value);
		}
		fprintf(file, "\n");
	}
	if (part->stock)
		dump_stock(file, part->stock);
}


static gboolean dump_prm_traverse(gpointer key, gpointer value, gpointer data)
{
	struct part *p = key;
	FILE *file = data;

	(void) value;
	part_dump(file, p);
	return FALSE;
}


void parts_dump(FILE *file)
{
	g_tree_foreach(tree, dump_prm_traverse, (void *) file);
}


/* ----- Currencies -------------------------------------------------------- */


static struct currency *currencies = NULL;


const struct currency *currency_lookup(const char *name)
{
	const struct currency *c;

	for (c = currencies; c; c = c->next)
		if (c->name == name)
			break;
	return c;
}


double currency_convert(const struct currency *from, const struct currency *to,
    double value)
{
	const struct exchange *ex;

	for (ex = from->exchange; ex; ex = ex->next)
		if (ex->dst == to)
			return ex->rate*value;
	fprintf(stderr, "cannot convert %s to %s\n", from->name, to->name);
	exit(1);
}


struct currency *currency_add(const char *name)
{
	struct currency **c;

	for (c = &currencies; *c; c = &(*c)->next)
		if ((*c)->name == name)
			return *c;
	*c = alloc_type(struct currency);
	(*c)->name = name;
	(*c)->exchange = NULL;
	(*c)->next = NULL;
	return *c;
}


void currency_exchange(struct currency *from, const struct currency *to,
    double rate)
{
	struct exchange **ex;

	for (ex = &from->exchange; *ex; ex = &(*ex)->next)
		if ((*ex)->dst == to)
			yyerrorf("exchange %s -> %s is already defined",
			    from->name, to->name);
	*ex = alloc_type(struct exchange);
	(*ex)->dst = to;
	(*ex)->rate = rate;
	(*ex)->next = NULL;
}


/* ----- Provider database ------------------------------------------------- */


static struct provider *providers = NULL;


struct provider *provider_lookup(const char *name)
{
	struct provider *p;

	for (p = providers; p; p = p->next)
		if (p->name == name)
			break;
	return p;
}


struct provider *provider_add(const char *name)
{
	struct provider *p;

	p = provider_lookup(name);
	if (p)
		return p;

	p = alloc_type(struct provider);
	p->name = name;
	p->curr = NULL;
	p->shipping = 0;
	p->minimum = 0;
	p->next = providers;
	providers = p;
	return p;
}


/* ----- Part search (by characteristics) ---------------------------------- */


struct sel_prm_data {
	struct param *param;
	const struct part **res;
	int n_res;
};


static struct param *convert_vars(struct param *vars, const struct action *act)
{
	struct param *res = NULL, **last = &res;

	convert_params(&vars, act->fields, &last);
	convert_params(&vars, act->rules, &last);
	free_vars(vars);
	return res;
}


/*
 * @@@ By matching fields (and not field names), we avoid having to check for
 * field compatibility. However, this also means that only fields that appear
 * in the same place in the hierarchy can be matched.
 *
 * For example, a tolerance TOL in T=R could thus never match the tolerance TOL
 * in T=C. This seems reasonable, but may need some more pondering.
 */

/*
 * @@@ We require all fields specified in the query to exist (and to match).
 * Could there be cases where this doesn't make sense ?
 */

static int params_match(const struct param *query, const struct param *part)
{
	const struct param *q, *p;

	for (q = query; q; q = q->next) {
		for (p = part; p; p = p->next) {
			if (q->u.field != p->u.field)
				continue;
			if (compare(q->u.field->fmt, &p->value, q->op,
			   &q->value))
				goto next;
			return 0;
		}
		return 0;
next:		;
	}
	return 1;
}


static gboolean sel_prm_traverse(gpointer key, gpointer value, gpointer data)
{
	struct part *p = key;
	struct sel_prm_data *d = data;

	(void) value;
	if (!params_match(d->param, p->param))
		return FALSE;
	d->res = realloc(d->res, sizeof(const struct part *)*(d->n_res+1));
	if (!d->res)
		abort();
	d->res[d->n_res++] = key;
	return FALSE;
}


const struct part **select_parametric(struct param *vars,
    const struct action *act)
{
	struct sel_prm_data data = {
		.param = convert_vars(vars, act),
		.res = NULL,
		.n_res = 0,
	};

	g_tree_foreach(tree, sel_prm_traverse, (void *) &data);
	if (data.n_res)
		data.res[data.n_res] = NULL;
	return data.res;
}