From 4bec4883792f86cd835936113a9d39bebcf0344f Mon Sep 17 00:00:00 2001
From: David Vazgenovich Shakaryan <dvshakaryan@gmail.com>
Date: Sun, 15 May 2022 02:32:08 -0700
Subject: web: implement difficulty abstraction for stdev

---
 web/web_opts.c | 71 +++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 51 insertions(+), 20 deletions(-)

(limited to 'web/web_opts.c')

diff --git a/web/web_opts.c b/web/web_opts.c
index 553e05d..e1c5eb5 100644
--- a/web/web_opts.c
+++ b/web/web_opts.c
@@ -13,17 +13,53 @@
 #define PREFIX "dartboat_"
 
 int delay_ms = 1000;
+static int difficulty = 32;
+
+struct { int diff; double stdev; } DIFF_PRESETS[] = {
+	{ 0, 66.80}, // 10
+	{ 8, 40.24}, // 20
+	{16, 28.14}, // 30
+	{24, 21.35}, // 40
+	{32, 17.20}, // 50
+	{40, 14.34}, // 60
+	{48, 12.15}, // 70
+	{56, 10.36}, // 80
+	{64,  8.83}, // 90
+	{72,  7.48}, // 100
+	{80,  6.32}, // 110
+	{88,  5.34}, // 120
+	{99,  0.00}, // 167
+};
+#define NUM_DIFF_PRESETS (sizeof(DIFF_PRESETS) / sizeof(*DIFF_PRESETS))
 
 void set_delay(char *val)
 {
 	delay_ms = atoi(val);
 }
 
-void set_stdev(char *val)
+void set_stdev(int diff)
 {
-	double stdev = strtod(val, NULL);
-	if (isfinite(stdev))
-		horizontal_stdev = vertical_stdev = stdev;
+	if (diff < DIFF_PRESETS[0].diff)
+		diff = DIFF_PRESETS[0].diff;
+	else if (diff > DIFF_PRESETS[NUM_DIFF_PRESETS - 1].diff)
+		diff = DIFF_PRESETS[NUM_DIFF_PRESETS - 1].diff;
+
+	size_t ind = 1;
+	while (ind < NUM_DIFF_PRESETS - 1 && DIFF_PRESETS[ind].diff <= diff)
+		ind++;
+
+	double step = (DIFF_PRESETS[ind - 1].stdev - DIFF_PRESETS[ind].stdev) /
+		(DIFF_PRESETS[ind].diff - DIFF_PRESETS[ind - 1].diff);
+	horizontal_stdev = vertical_stdev = DIFF_PRESETS[ind - 1].stdev -
+		((diff - DIFF_PRESETS[ind - 1].diff) * step);
+}
+
+void set_difficulty(char *val)
+{
+	int diff = atoi(val);
+	difficulty = diff < 0 ? 0 : diff > 99 ? 99 : diff;
+
+	set_stdev(difficulty);
 }
 
 char *prefix_opt(char *opt)
@@ -53,34 +89,29 @@ void read_delay()
 	free(val);
 }
 
-void read_stdev()
+void read_difficulty()
 {
-	char *val = read_opt("stdev");
+	char *val = read_opt("difficulty");
 	if (!val) return;
 
-	set_stdev(val);
+	set_difficulty(val);
 	free(val);
 }
 
 void opts_init()
 {
+	// TODO call only when no stored diff setting
+	set_stdev(difficulty);
+
 	read_delay();
-	read_stdev();
+	read_difficulty();
 
 	char buf[64];
 	sprintf(buf, "%d", delay_ms);
 	dom_set_value("#delay", buf);
 
-	int len = sprintf(buf, "%4.2f", horizontal_stdev);
-	char *dot = strchr(buf, '.');
-	if (dot) {
-		for (char *ptr = buf + len - 1; ptr >= dot; --ptr) {
-			if (*ptr != '0' && *ptr != '.')
-				break;
-			*ptr = 0;
-		}
-	}
-	dom_set_value("#stdev", buf);
+	sprintf(buf, "%d", difficulty);
+	dom_set_value("#difficulty", buf);
 }
 
 void store_opt(char *opt, char  *val)
@@ -95,8 +126,8 @@ void set_opt(char *opt, char *val)
 {
 	if (!strcmp(opt, "delay"))
 		set_delay(val);
-	else if (!strcmp(opt, "stdev"))
-		set_stdev(val);
+	else if (!strcmp(opt, "difficulty"))
+		set_difficulty(val);
 	else
 		return;
 
-- 
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