128 lines
3.7 KiB
Bash
Executable file
128 lines
3.7 KiB
Bash
Executable file
#!/bin/bash
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# Generate timezone offset lookup table based on longitude
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# Samples at multiple latitudes to handle political boundaries
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set -e
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OUTPUT_FILE="src/location/timezone_offsets.zig"
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TEMP_FILE=$(mktemp)
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# Latitudes to sample (equator, +/-30)
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LATITUDES=(0 30 -30)
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echo "Generating timezone offset table..."
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echo "This will make 1080 API calls (360 longitudes × 3 latitudes)"
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echo
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# Start the output file
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cat > "$TEMP_FILE" << 'EOF'
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// Auto-generated timezone offset table
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// Generated by scripts/generate_timezone_table.sh
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//
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// Maps longitude (0-359) to UTC offset in minutes
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// Sampled at latitudes: 0°, 30°N, 30°S and uses most common offset
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const std = @import("std");
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/// Timezone offset in minutes from UTC for each degree of longitude (0-359)
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/// Negative values = west of UTC, positive = east of UTC
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pub const timezone_offsets: [360]i16 = .{
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EOF
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# For each longitude
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for lon in {-180..179}; do
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# Normalize to 0-359 for array index
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array_idx=$((lon + 180))
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echo -n "Processing longitude $lon ($((array_idx + 1))/360)..." >&2
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# Collect offsets from all latitudes
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declare -A offset_counts
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for lat in "${LATITUDES[@]}"; do
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# Query the API
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response=$(curl -s "https://tools.maximmaeder.com/t/get-timezone-by-coordinates/?latitude=$lat&longitude=$lon")
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# Extract offset (format: "UTC+05:30" or "UTC-08:00")
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offset=$(echo "$response" | grep -oP 'UTC[+-]\d{2}:\d{2}' | head -1)
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if [ -z "$offset" ]; then
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echo " failed to get timezone for lat=$lat, lon=$lon" >&2
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continue
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fi
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# Convert to minutes
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sign=$(echo "$offset" | grep -oP '[+-]')
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hours=$(echo "$offset" | grep -oP '\d{2}' | head -1)
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mins=$(echo "$offset" | grep -oP '\d{2}' | tail -1)
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total_mins=$((hours * 60 + mins))
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if [ "$sign" = "-" ]; then
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total_mins=$((total_mins * -1))
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fi
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# Count occurrences
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offset_counts[$total_mins]=$((${offset_counts[$total_mins]:-0} + 1))
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# Rate limit
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sleep 0.1
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done
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# Find most common offset
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max_count=0
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most_common_offset=0
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for offset in "${!offset_counts[@]}"; do
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if [ "${offset_counts[$offset]}" -gt "$max_count" ]; then
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max_count="${offset_counts[$offset]}"
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most_common_offset="$offset"
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fi
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done
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echo " → ${most_common_offset} minutes" >&2
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# Add to array (with comma except for last element)
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if [ "$array_idx" -eq 359 ]; then
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echo " $most_common_offset," >> "$TEMP_FILE"
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else
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echo " $most_common_offset," >> "$TEMP_FILE"
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fi
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unset offset_counts
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done
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# Close the array
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cat >> "$TEMP_FILE" << 'EOF'
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};
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/// Get timezone offset in minutes for a given longitude
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/// longitude: -180 to 180
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/// Returns: offset in minutes from UTC
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pub fn getTimezoneOffset(longitude: f32) i16 {
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// Normalize to 0-359
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const normalized = @mod(@as(i32, @intFromFloat(@round(longitude))) + 180, 360);
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return timezone_offsets[@intCast(normalized)];
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}
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test "timezone offset lookup" {
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// London (0°) should be close to UTC
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const london_offset = getTimezoneOffset(0.0);
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try std.testing.expect(london_offset >= -60 and london_offset <= 60);
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// New York (-74°) should be around UTC-5 (-300 minutes)
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const ny_offset = getTimezoneOffset(-74.0);
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try std.testing.expect(ny_offset >= -360 and ny_offset <= -240);
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// Tokyo (139°) should be around UTC+9 (540 minutes)
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const tokyo_offset = getTimezoneOffset(139.0);
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try std.testing.expect(tokyo_offset >= 480 and tokyo_offset <= 600);
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}
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EOF
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# Move to final location
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mv "$TEMP_FILE" "$OUTPUT_FILE"
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echo
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echo "Generated $OUTPUT_FILE"
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echo "Running zig fmt..."
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zig fmt "$OUTPUT_FILE"
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echo "Done!"
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