{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Guitar Tab Interchange Format",
  "description": "A portable, renderer-friendly format for guitar tablature, chord/lyric sheets, repeats, annotations, and beat-level playback anchors.",
  "type": "object",
  "additionalProperties": false,
  "required": ["format", "id", "metadata", "instrument", "arrangements"],
  "properties": {
    "$schema": { "type": "string" },
    "format": { "const": "guitar-tab/v1" },
    "id": { "$ref": "#/$defs/id" },
    "metadata": { "$ref": "#/$defs/metadata" },
    "instrument": { "$ref": "#/$defs/instrument" },
    "timing": { "$ref": "#/$defs/timing" },
    "legend": {
      "type": "array",
      "items": { "$ref": "#/$defs/legendItem" },
      "default": []
    },
    "arrangements": {
      "type": "array",
      "minItems": 1,
      "items": { "$ref": "#/$defs/arrangement" }
    },
    "extensions": { "$ref": "#/$defs/extensions" }
  },
  "$defs": {
    "id": {
      "type": "string",
      "pattern": "^[a-z0-9]+(?:-[a-z0-9]+)*$"
    },
    "extensions": {
      "type": "object",
      "description": "Namespaced vendor data. Keys should use reverse-domain notation.",
      "additionalProperties": true,
      "default": {}
    },
    "metadata": {
      "type": "object",
      "additionalProperties": false,
      "required": ["title", "artists"],
      "properties": {
        "title": { "type": "string", "minLength": 1 },
        "artists": {
          "type": "array",
          "minItems": 1,
          "items": { "type": "string", "minLength": 1 }
        },
        "arranger": { "type": "string" },
        "album": { "type": "string" },
        "source": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "label": { "type": "string" },
            "file": { "type": "string" },
            "url": { "type": "string", "format": "uri" },
            "pages": {
              "type": "array",
              "items": { "type": "integer", "minimum": 1 },
              "uniqueItems": true
            }
          }
        },
        "links": {
          "type": "array",
          "items": {
            "type": "object",
            "additionalProperties": false,
            "required": ["label", "url"],
            "properties": {
              "label": { "type": "string", "minLength": 1 },
              "url": { "type": "string", "format": "uri" }
            }
          }
        }
      }
    },
    "instrument": {
      "type": "object",
      "additionalProperties": false,
      "required": ["type", "strings", "tuning", "capo"],
      "properties": {
        "type": { "const": "guitar" },
        "strings": { "type": "integer", "minimum": 1, "maximum": 18 },
        "capo": { "type": "integer", "minimum": 0, "maximum": 24 },
        "tuningName": { "type": "string" },
        "tuning": {
          "type": "array",
          "minItems": 1,
          "items": {
            "type": "object",
            "additionalProperties": false,
            "required": ["string", "label", "pitch"],
            "properties": {
              "string": { "type": "integer", "minimum": 1 },
              "label": { "type": "string", "minLength": 1, "maxLength": 3 },
              "pitch": { "type": "string", "pattern": "^[A-G](?:#|b)?-?[0-9]+$" }
            }
          }
        }
      }
    },
    "timing": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "tempoBpm": { "type": "number", "exclusiveMinimum": 0, "maximum": 240 },
        "timeSignature": {
          "type": "object",
          "additionalProperties": false,
          "required": ["beats", "beatValue"],
          "properties": {
            "beats": { "type": "integer", "minimum": 1, "maximum": 32 },
            "beatValue": { "type": "integer", "enum": [1, 2, 4, 8, 16, 32] }
          }
        }
      }
    },
    "legendItem": {
      "type": "object",
      "additionalProperties": false,
      "required": ["token", "label"],
      "properties": {
        "token": { "type": "string", "minLength": 1 },
        "label": { "type": "string", "minLength": 1 },
        "kind": {
          "type": "string",
          "enum": ["technique", "stroke", "rhythm", "other"]
        }
      }
    },
    "arrangement": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "title", "sections"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "title": { "type": "string", "minLength": 1 },
        "description": { "type": "string" },
        "difficulty": { "type": "string" },
        "sections": {
          "type": "array",
          "minItems": 1,
          "items": { "$ref": "#/$defs/section" }
        },
        "extensions": { "$ref": "#/$defs/extensions" }
      }
    },
    "section": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "title", "blocks"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "title": { "type": "string", "minLength": 1 },
        "repeat": { "$ref": "#/$defs/repeat" },
        "blocks": {
          "type": "array",
          "minItems": 1,
          "items": {
            "oneOf": [
              { "$ref": "#/$defs/tabBlock" },
              { "$ref": "#/$defs/chordLyricsBlock" }
            ]
          }
        },
        "extensions": { "$ref": "#/$defs/extensions" }
      }
    },
    "repeat": {
      "type": "object",
      "additionalProperties": false,
      "required": ["times"],
      "properties": {
        "times": { "type": "integer", "minimum": 2 }
      }
    },
    "tabBlock": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "type", "bars"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "type": { "const": "tab" },
        "label": { "type": "string" },
        "bars": {
          "type": "array",
          "minItems": 1,
          "items": { "$ref": "#/$defs/bar" }
        },
        "repeat": { "$ref": "#/$defs/repeat" },
        "extensions": { "$ref": "#/$defs/extensions" }
      }
    },
    "bar": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "columnCount", "rows"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "columnCount": { "type": "integer", "minimum": 1, "maximum": 4096 },
        "beats": { "type": "number", "exclusiveMinimum": 0, "maximum": 32 },
        "barline": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "left": { "$ref": "#/$defs/barline" },
            "right": { "$ref": "#/$defs/barline" }
          }
        },
        "rows": {
          "type": "array",
          "minItems": 1,
          "items": { "$ref": "#/$defs/tabRow" }
        },
        "lyrics": {
          "type": "array",
          "items": { "$ref": "#/$defs/positionedText" }
        },
        "chords": {
          "type": "array",
          "items": { "$ref": "#/$defs/positionedText" }
        },
        "markers": {
          "type": "array",
          "items": { "$ref": "#/$defs/marker" }
        },
        "events": {
          "type": "array",
          "items": { "$ref": "#/$defs/event" }
        },
        "notes": { "type": "string" },
        "extensions": { "$ref": "#/$defs/extensions" }
      }
    },
    "barline": {
      "type": "string",
      "enum": ["none", "single", "double", "repeatStart", "repeatEnd", "final"]
    },
    "tabRow": {
      "type": "object",
      "additionalProperties": false,
      "required": ["string", "text"],
      "properties": {
        "string": { "type": "integer", "minimum": 1 },
        "text": { "type": "string", "minLength": 1 }
      }
    },
    "positionedText": {
      "type": "object",
      "additionalProperties": false,
      "required": ["text"],
      "properties": {
        "text": { "type": "string", "minLength": 1 },
        "atColumn": { "type": "integer", "minimum": 0 }
      }
    },
    "marker": {
      "type": "object",
      "additionalProperties": false,
      "required": ["atColumn", "token"],
      "properties": {
        "atColumn": { "type": "integer", "minimum": 0 },
        "token": { "type": "string", "minLength": 1 },
        "label": { "type": "string" }
      }
    },
    "event": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "atBeat", "durationBeats", "notes"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "atBeat": { "type": "number", "minimum": 0 },
        "durationBeats": { "type": "number", "exclusiveMinimum": 0 },
        "notes": {
          "type": "array",
          "minItems": 1,
          "items": { "$ref": "#/$defs/note" }
        },
        "label": { "type": "string" }
      }
    },
    "note": {
      "type": "object",
      "additionalProperties": false,
      "required": ["string", "from", "to"],
      "properties": {
        "string": { "type": "integer", "minimum": 1 },
        "fret": { "type": "integer", "minimum": 0 },
        "muted": { "type": "boolean" },
        "from": { "type": "integer", "minimum": 0 },
        "to": { "type": "integer", "minimum": 1 },
        "techniques": {
          "type": "array",
          "items": { "type": "string", "minLength": 1 },
          "uniqueItems": true
        }
      },
      "anyOf": [
        { "required": ["fret"] },
        { "properties": { "muted": { "const": true } }, "required": ["muted"] }
      ]
    },
    "chordLyricsBlock": {
      "type": "object",
      "additionalProperties": false,
      "required": ["id", "type", "lines"],
      "properties": {
        "id": { "$ref": "#/$defs/id" },
        "type": { "const": "chordLyrics" },
        "label": { "type": "string" },
        "lines": {
          "type": "array",
          "minItems": 1,
          "items": {
            "type": "object",
            "additionalProperties": false,
            "required": ["id", "spans"],
            "properties": {
              "id": { "$ref": "#/$defs/id" },
              "spans": {
                "type": "array",
                "minItems": 1,
                "items": {
                  "type": "object",
                  "additionalProperties": false,
                  "required": ["id", "text"],
                  "properties": {
                    "id": { "$ref": "#/$defs/id" },
                    "text": { "type": "string" },
                    "chord": { "type": "string" }
                  }
                }
              }
            }
          }
        },
        "repeat": { "$ref": "#/$defs/repeat" },
        "extensions": { "$ref": "#/$defs/extensions" }
      }
    }
  }
}