Add pricing.md

Author: danlooo

website/.gitignore

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 !overview.md
 !background.md
+!pricing.md
 
 node_modules
 .quarto

website/docs/pricing.md

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+# Pricing
+
+This project is creating free and open-source software under the MIT license.
+There are plenty of ways to run the workflow locally after downloading the [data](/background-gfm.html#data).
+However, the workflow can be also be executed with [openEO at EODC](https://editor.openeo.org/?server=openeo.eodc.eu%2Fopeneo%2F1.2.0%2F) by enabling experimental processes and searching for 'rqadeforestation'.
+A preliminary price estimation can be calculated using the following tool:
+
+## openEO price calculator
+
+<div>
+
+<!-- added HTML form + script -->
+<form id="pricing-form" onsubmit="return false;" style="margin-top:1rem;">
+  <label>
+    Equi7 tiles:
+    <input id="tiles" type="number" min="0" step="1" value="1" style="width:6rem;">
+  </label>
+  <br style="line-height:0.6;">
+  <label>
+    Start date:
+    <input id="start" type="date">
+  </label>
+  <label style="margin-left:1rem;">
+    End date:
+    <input id="end" type="date">
+  </label>
+  <div style="margin-top:0.5rem;">
+    Price: <output id="price">0.00</output>
+  </div>
+</form>
+
+<script>
+(function(){
+  const tilesEl = document.getElementById('tiles');
+  const startEl = document.getElementById('start');
+  const endEl = document.getElementById('end');
+  const priceEl = document.getElementById('price');
+
+  const minDate = '2014-01-01';
+  const today = new Date();
+  const yyyy = today.getFullYear();
+  const mm = String(today.getMonth()+1).padStart(2,'0');
+  const dd = String(today.getDate()).padStart(2,'0');
+  const todayStr = `${yyyy}-${mm}-${dd}`;
+
+  startEl.min = minDate;
+  endEl.min = minDate;
+  startEl.max = todayStr;
+  endEl.max = todayStr;
+
+  startEl.value = minDate;
+  endEl.value = todayStr;
+
+  function parseDateInput(el){
+    const v = el.value;
+    if(!v) return null;
+    const d = new Date(v + 'T00:00:00Z');
+    return isNaN(d) ? null : d;
+  }
+
+  function compute(){
+    const tiles = Number(tilesEl.value) || 0;
+    const start = parseDateInput(startEl);
+    const end = parseDateInput(endEl);
+    if(!start || !end || end < start){
+      priceEl.textContent = '0.00';
+      return;
+    }
+    // duration in years (approx)
+    const msPerYear = 1000 * 60 * 60 * 24 * 365.25;
+    const years = (end - start) / msPerYear;
+    const product = tiles * years;
+    priceEl.textContent = product.toFixed(2);
+  }
+
+  tilesEl.addEventListener('input', compute);
+  startEl.addEventListener('change', compute);
+  endEl.addEventListener('change', compute);
+
+  // initial compute
+  compute();
+})();
+</script>
+</div>