feature: Optional OCR-Assisted Draft Pre-Fill
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voltsrage
@@ -0,0 +1,264 @@
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using Azure;
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using Azure.AI.DocumentIntelligence;
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using Microsoft.Extensions.Options;
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public class AzureDocumentOcrService : IOcrService
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{
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private const double DefaultTableConfidence = 0.75;
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private static readonly Dictionary<string, string> ClinicalLabelMap =
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new(StringComparer.OrdinalIgnoreCase)
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{
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["patient name"] = "patient.fullName",
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["name"] = "patient.fullName",
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["full name"] = "patient.fullName",
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["date of birth"] = "patient.dateOfBirth",
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["dob"] = "patient.dateOfBirth",
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["birth date"] = "patient.dateOfBirth",
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["sex"] = "patient.sex",
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["gender"] = "patient.sex",
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["admission date"] = "encounter.admissionDate",
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["admitted"] = "encounter.admissionDate",
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["department"] = "encounter.department",
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["ward"] = "encounter.department",
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["unit"] = "encounter.department",
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["room"] = "encounter.roomBed",
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["bed"] = "encounter.roomBed",
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["room/bed"] = "encounter.roomBed",
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["hr"] = "observation.HEART_RATE.value",
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["heart rate"] = "observation.HEART_RATE.value",
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["pulse"] = "observation.HEART_RATE.value",
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["temp"] = "observation.TEMP_C.value",
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["temperature"] = "observation.TEMP_C.value",
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["bp sys"] = "observation.BP_SYSTOLIC.value",
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["systolic"] = "observation.BP_SYSTOLIC.value",
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["bp dia"] = "observation.BP_DIASTOLIC.value",
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["diastolic"] = "observation.BP_DIASTOLIC.value",
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["rr"] = "observation.RESP_RATE.value",
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["resp rate"] = "observation.RESP_RATE.value",
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["respiratory rate"] = "observation.RESP_RATE.value",
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["spo2"] = "observation.SPO2.value",
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["o2 sat"] = "observation.SPO2.value",
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["oxygen saturation"] = "observation.SPO2.value",
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};
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private static readonly HashSet<string> TimestampHeaders = new(StringComparer.OrdinalIgnoreCase)
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{
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"time", "date", "datetime", "date/time", "recorded", "recorded at", "timestamp"
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};
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private static readonly HashSet<string> GenericTableHeaders = new(StringComparer.OrdinalIgnoreCase)
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{
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"label", "name", "parameter", "field", "item", "value", "result", "reading"
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};
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private readonly DocumentIntelligenceClient _client;
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private readonly ILogger<AzureDocumentOcrService> _logger;
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public AzureDocumentOcrService(
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IOptions<OcrOptions> options,
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ILogger<AzureDocumentOcrService> logger)
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{
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var opts = options.Value.Azure;
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_client = new DocumentIntelligenceClient(
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new Uri(opts.Endpoint),
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new AzureKeyCredential(opts.ApiKey));
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_logger = logger;
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}
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public async Task<OcrExtractionResult> ExtractAsync(
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Stream documentStream, string contentType)
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{
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var sw = System.Diagnostics.Stopwatch.StartNew();
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var content = BinaryData.FromStream(documentStream);
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var operation = await _client.AnalyzeDocumentAsync(
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WaitUntil.Completed,
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"prebuilt-document",
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content);
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var result = operation.Value;
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var fields = new List<OcrExtractedField>();
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foreach (var kv in result.KeyValuePairs ?? [])
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{
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if (kv.Key?.Content is null || kv.Value?.Content is null) continue;
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var fieldName = MapAzureKeyToFieldName(kv.Key.Content);
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if (fieldName is null) continue;
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fields.Add(new OcrExtractedField(
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fieldName,
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kv.Value.Content,
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kv.Confidence));
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}
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foreach (var table in result.Tables ?? [])
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{
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fields.AddRange(ExtractTableObservations(table));
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}
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var rawText = string.Join("\n", (result.Pages ?? [])
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.SelectMany(p => p.Lines?.Select(l => l.Content) ?? []));
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sw.Stop();
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return new OcrExtractionResult(fields, rawText, (int)sw.ElapsedMilliseconds);
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}
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private static string? MapAzureKeyToFieldName(string key)
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{
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var normalized = key.Trim();
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if (normalized.Length == 0)
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return null;
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return ClinicalLabelMap.GetValueOrDefault(normalized);
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}
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private static List<OcrExtractedField> ExtractTableObservations(DocumentTable table)
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{
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var fields = new List<OcrExtractedField>();
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if (table.Cells is null || table.Cells.Count == 0)
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return fields;
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if (table.ColumnCount == 2)
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{
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var labelValueFields = ExtractLabelValueTable(table);
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if (labelValueFields.Count > 0)
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return labelValueFields;
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}
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return ExtractGridTable(table);
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}
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private static List<OcrExtractedField> ExtractLabelValueTable(DocumentTable table)
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{
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var fields = new List<OcrExtractedField>();
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var dataStartRow = HasGenericHeaderRow(table.Cells) ? 1 : 0;
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for (var row = dataStartRow; row < table.RowCount; row++)
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{
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var key = GetCellContent(table.Cells, row, 0);
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var value = GetCellContent(table.Cells, row, 1);
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if (string.IsNullOrWhiteSpace(key) || string.IsNullOrWhiteSpace(value))
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continue;
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var fieldName = MapAzureKeyToFieldName(key);
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if (fieldName is null)
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continue;
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fields.Add(new OcrExtractedField(fieldName, value.Trim(), DefaultTableConfidence));
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}
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return fields;
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}
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private static List<OcrExtractedField> ExtractGridTable(DocumentTable table)
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{
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var fields = new List<OcrExtractedField>();
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var headerCells = table.Cells
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.Where(c => c.RowIndex == 0)
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.OrderBy(c => c.ColumnIndex)
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.ToList();
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if (headerCells.Count == 0)
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return fields;
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var columnMappings = new Dictionary<int, string?>();
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foreach (var headerCell in headerCells)
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{
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columnMappings[headerCell.ColumnIndex] = MapTableHeader(headerCell.Content);
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}
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var observationCodes = columnMappings.Values
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.Where(v => v is not null and not "recordedAt")
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.Cast<string>()
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.Distinct()
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.ToList();
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if (observationCodes.Count == 0)
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return fields;
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for (var row = 1; row < table.RowCount; row++)
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{
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string? recordedAt = null;
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foreach (var cell in table.Cells.Where(c => c.RowIndex == row))
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{
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if (!columnMappings.TryGetValue(cell.ColumnIndex, out var mapping)
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|| mapping is null
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|| string.IsNullOrWhiteSpace(cell.Content))
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{
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continue;
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}
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var content = cell.Content.Trim();
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if (mapping == "recordedAt")
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{
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recordedAt = content;
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continue;
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}
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fields.Add(new OcrExtractedField(
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$"observation.{mapping}.value",
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content,
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DefaultTableConfidence));
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}
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if (recordedAt is null)
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continue;
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foreach (var code in observationCodes)
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{
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fields.Add(new OcrExtractedField(
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$"observation.{code}.recordedAt",
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recordedAt,
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DefaultTableConfidence));
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}
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}
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return fields;
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}
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private static string? MapTableHeader(string? header)
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{
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if (string.IsNullOrWhiteSpace(header))
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return null;
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var normalized = header.Trim();
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if (TimestampHeaders.Contains(normalized))
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return "recordedAt";
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var fieldName = MapAzureKeyToFieldName(normalized);
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if (fieldName is null)
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return null;
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const string observationPrefix = "observation.";
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const string valueSuffix = ".value";
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if (fieldName.StartsWith(observationPrefix, StringComparison.Ordinal)
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&& fieldName.EndsWith(valueSuffix, StringComparison.Ordinal))
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{
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return fieldName[observationPrefix.Length..^valueSuffix.Length];
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}
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return null;
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}
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private static bool HasGenericHeaderRow(IReadOnlyList<DocumentTableCell> cells)
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{
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var headerCells = cells.Where(c => c.RowIndex == 0).ToList();
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if (headerCells.Count != 2)
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return false;
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return headerCells.All(c =>
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GenericTableHeaders.Contains(c.Content?.Trim() ?? string.Empty));
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}
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private static string? GetCellContent(
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IReadOnlyList<DocumentTableCell> cells, int row, int column)
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{
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return cells
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.FirstOrDefault(c => c.RowIndex == row && c.ColumnIndex == column)
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?.Content;
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}
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}
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