<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 
           elementFormDefault="unqualified"
           attributeFormDefault="unqualified">
  <xs:annotation>
    <xs:documentation>
      Zwift Workout File Format Schema
      This schema defines the structure of Zwift workout files (.zwo format)
      Extended to allow custom attributes for round-trip data preservation
    </xs:documentation>
  </xs:annotation>

  <!-- Root element -->
  <xs:element name="workout_file">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="author" type="xs:string" minOccurs="0"/>
        <xs:element name="name" type="xs:string"/>
        <xs:element name="description" type="xs:string" minOccurs="0"/>
        <xs:element name="sportType" type="sportType_t"/>
        <xs:element name="tags" minOccurs="0">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="tag" type="xs:string" minOccurs="0" maxOccurs="unbounded"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="workout" type="workout_t"/>
      </xs:sequence>
      <xs:anyAttribute namespace="##any" processContents="lax"/>
    </xs:complexType>
  </xs:element>

  <!-- Sport type enumeration -->
  <xs:simpleType name="sportType_t">
    <xs:restriction base="xs:string">
      <xs:enumeration value="bike"/>
      <xs:enumeration value="run"/>
    </xs:restriction>
  </xs:simpleType>

  <!-- Workout container -->
  <xs:complexType name="workout_t">
    <xs:choice minOccurs="0" maxOccurs="unbounded">
      <xs:element name="SteadyState" type="steadyState_t"/>
      <xs:element name="Warmup" type="ramp_t"/>
      <xs:element name="Ramp" type="ramp_t"/>
      <xs:element name="Cooldown" type="ramp_t"/>
      <xs:element name="IntervalsT" type="intervalsT_t"/>
      <xs:element name="FreeRide" type="freeRide_t"/>
    </xs:choice>
  </xs:complexType>

  <!-- SteadyState interval -->
  <xs:complexType name="steadyState_t">
    <xs:sequence>
      <xs:element name="textevent" type="textevent_t" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="Duration" type="xs:decimal" use="required"/>
    <xs:attribute name="Power" type="powerValue_t" use="optional"/>
    <xs:attribute name="pace" type="xs:decimal" use="optional"/>
    <xs:attribute name="Cadence" type="xs:int" use="optional"/>
    <xs:anyAttribute namespace="##any" processContents="lax"/>
  </xs:complexType>

  <!-- Ramp interval (Warmup, Ramp, Cooldown) -->
  <xs:complexType name="ramp_t">
    <xs:sequence>
      <xs:element name="textevent" type="textevent_t" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="Duration" type="xs:decimal" use="required"/>
    <xs:attribute name="PowerLow" type="powerValue_t" use="optional"/>
    <xs:attribute name="PowerHigh" type="powerValue_t" use="optional"/>
    <xs:attribute name="pace" type="xs:decimal" use="optional"/>
    <xs:attribute name="Cadence" type="xs:int" use="optional"/>
    <xs:anyAttribute namespace="##any" processContents="lax"/>
  </xs:complexType>

  <!-- IntervalsT (repeated intervals) -->
  <xs:complexType name="intervalsT_t">
    <xs:sequence>
      <xs:element name="textevent" type="textevent_t" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="Repeat" type="xs:int" use="required"/>
    <xs:attribute name="OnDuration" type="xs:decimal" use="required"/>
    <xs:attribute name="OffDuration" type="xs:decimal" use="required"/>
    <xs:attribute name="OnPower" type="powerValue_t" use="optional"/>
    <xs:attribute name="OffPower" type="powerValue_t" use="optional"/>
    <xs:attribute name="pace" type="xs:decimal" use="optional"/>
    <xs:attribute name="Cadence" type="xs:int" use="optional"/>
    <xs:attribute name="CadenceResting" type="xs:int" use="optional"/>
    <xs:anyAttribute namespace="##any" processContents="lax"/>
  </xs:complexType>

  <!-- FreeRide interval -->
  <xs:complexType name="freeRide_t">
    <xs:sequence>
      <xs:element name="textevent" type="textevent_t" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:attribute name="Duration" type="xs:decimal" use="required"/>
    <xs:attribute name="Cadence" type="xs:int" use="optional"/>
    <xs:attribute name="FlatRoad" type="xs:int" use="optional"/>
  </xs:complexType>

  <!-- Text event (coaching cue) -->
  <xs:complexType name="textevent_t">
    <xs:attribute name="message" type="xs:string" use="required"/>
    <xs:attribute name="timeoffset" type="xs:decimal" use="optional"/>
    <xs:attribute name="distoffset" type="xs:decimal" use="optional"/>
  </xs:complexType>

  <!-- Power value type (FTP percentage 0.0 to 3.0) -->
  <xs:simpleType name="powerValue_t">
    <xs:restriction base="xs:decimal">
      <xs:minInclusive value="0.0"/>
      <xs:maxInclusive value="3.0"/>
    </xs:restriction>
  </xs:simpleType>
</xs:schema>
