{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://basicstack.de/schemas/expense/canonical/v1.1.0.json",
  "title": "Expense (canonical) v1.1.0",
  "description": "Kanonische Reisekostenstruktur. Additive gegenüber v1.0.0: expense_items[] erhalten ein optionales allocations[]-Array, mit dem einzelne Zeilen auf mehrere Projekte prozentual oder absolut aufgeteilt werden können. Das top-level project_assignment ist optional (für Vorgänge ohne Zeilen-Splits) — es gilt als Default-Zuordnung für alle items ohne allocations. OPA erzwingt: pro Item entweder top-level project_assignment oder item.allocations, nicht beides zugleich; alle Allocations eines Items im selben Modus; Summenerhalt (percentage=100.00 bzw. amount=item.amount).",
  "type": "object",
  "additionalProperties": false,
  "required": ["schema", "workflow_id", "employee_id", "trip", "currency", "total_amount", "expense_items"],
  "properties": {
    "schema": {
      "type": "object",
      "additionalProperties": false,
      "required": ["name", "version"],
      "properties": {
        "name":    { "const": "expense.canonical" },
        "version": { "const": "1.1.0" }
      }
    },
    "workflow_id": {
      "type": "string",
      "pattern": "^WF-[0-9]{4}-[0-9]{4,}$"
    },
    "employee_id": {
      "type": "string",
      "pattern": "^EMP-[0-9]+$"
    },
    "trip": {
      "type": "object",
      "additionalProperties": false,
      "required": ["start_date", "end_date", "destination"],
      "properties": {
        "start_date":  { "type": "string", "format": "date" },
        "end_date":    { "type": "string", "format": "date" },
        "destination": { "type": "string", "minLength": 1, "maxLength": 200 },
        "purpose":     { "type": "string", "maxLength": 500 }
      }
    },
    "currency": {
      "type": "string",
      "pattern": "^[A-Z]{3}$"
    },
    "total_amount": {
      "type": "string",
      "pattern": "^-?[0-9]+\\.[0-9]{2}$"
    },
    "project_assignment": {
      "description": "Optional. Default-Projektzuordnung für alle items ohne eigenes allocations[]. Wenn ein Item eigene allocations hat, wird dieser Default für dieses Item NICHT angewendet.",
      "type": "object",
      "additionalProperties": false,
      "required": ["project_code", "cost_center", "source_attestation_ref"],
      "properties": {
        "project_code": { "type": "string", "pattern": "^P-[0-9]+$" },
        "cost_center":  { "type": "string", "pattern": "^CC-[0-9]+$" },
        "source_attestation_ref": {
          "type": "string",
          "pattern": "^sha256:[0-9a-f]{64}$"
        }
      }
    },
    "expense_items": {
      "type": "array",
      "minItems": 1,
      "maxItems": 200,
      "items": {
        "type": "object",
        "additionalProperties": false,
        "required": ["type", "amount", "incurred_on"],
        "properties": {
          "type": {
            "type": "string",
            "enum": ["HOTEL", "MEALS", "TRANSPORT_FLIGHT", "TRANSPORT_RAIL", "TRANSPORT_CAR", "PARKING", "COMMUNICATION", "CONFERENCE_FEE", "OTHER"]
          },
          "amount":      { "type": "string", "pattern": "^-?[0-9]+\\.[0-9]{2}$" },
          "incurred_on": { "type": "string", "format": "date" },
          "description": { "type": "string", "maxLength": 500 },
          "receipt_ref": {
            "type": "string",
            "pattern": "^pii://[A-Za-z0-9/._-]+$"
          },
          "allocations": {
            "description": "Optional. Aufteilung dieser Zeile auf ein oder mehrere Projekte. Wenn gesetzt, überschreibt das top-level project_assignment für dieses Item. Alle Entries desselben Items MÜSSEN denselben mode haben (OPA-Regel). Bei mode=percentage: Summe der percentage == 100.00. Bei mode=absolute: Summe der amount == item.amount.",
            "type": "array",
            "minItems": 1,
            "maxItems": 50,
            "items": {
              "type": "object",
              "additionalProperties": false,
              "required": ["project_code", "cost_center", "mode", "source_attestation_ref"],
              "properties": {
                "project_code": { "type": "string", "pattern": "^P-[0-9]+$" },
                "cost_center":  { "type": "string", "pattern": "^CC-[0-9]+$" },
                "mode":         { "enum": ["percentage", "absolute"] },
                "percentage": {
                  "type": "string",
                  "pattern": "^(100\\.00|[0-9]{1,2}\\.[0-9]{2})$",
                  "description": "Vorhanden wenn mode=percentage; abwesend sonst. Zwei Nachkommastellen, 0.00..100.00."
                },
                "amount": {
                  "type": "string",
                  "pattern": "^-?[0-9]+\\.[0-9]{2}$",
                  "description": "Vorhanden wenn mode=absolute; abwesend sonst."
                },
                "source_attestation_ref": {
                  "type": "string",
                  "pattern": "^sha256:[0-9a-f]{64}$",
                  "description": "SHA-256 der Query Attestation (ds:expense-db-app / project_assignments), aus der dieses project_code+cost_center stammt."
                }
              },
              "allOf": [
                {
                  "if": { "properties": { "mode": { "const": "percentage" } }, "required": ["mode"] },
                  "then": { "required": ["percentage"], "not": { "required": ["amount"] } }
                },
                {
                  "if": { "properties": { "mode": { "const": "absolute" } }, "required": ["mode"] },
                  "then": { "required": ["amount"], "not": { "required": ["percentage"] } }
                }
              ]
            }
          }
        }
      }
    }
  }
}