// Copyright 2023 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// This schema constrains a module.cue file. This form constrains module.cue files
// outside of the main module. For the module.cue file in a main module, the schema
// is less restrictive, because wherever #Semver is used, a less specific version may be
// used instead, which will be rewritten to the canonical form by the cue command tooling.
// To check against that form,

// versions holds an element for each supported version
// of the schema. The version key specifies that
// the schema covers all versions from then until the
// next version present in versions, or until the current CUE version,
// whichever is earlier.
versions: [string]: {
	// #File represents the overarching module file schema.
	#File!: {
		// We always require the language version, as we use
		// that to determine how to parse the file itself.
		// Note that this schema is not used by [ParseLegacy]
		// because legacy module.cue files did not support
		// language.version field.
		language!: version!: string
	}

	// #Strict can be unified with the top level schema to enforce the strict version
	// of the schema required when publishing a module.
	#Strict!: _
}

versions: "v0.8.0-alpha.0": {
	// Define this version in terms of the later versions
	// rather than the other way around, so that
	// the latest version is clearest.
	versions["v0.9.0-alpha.0"]

	// The source field was added in v0.9.0, so "remove"
	// it here by marking it as an error when used.
	#File: source?: _errorSourceFieldRequiredVersion
}

versions: "v0.9.0-alpha.0": {
	#File: {
		// module indicates the module's path.
		module?: #Module | ""

		// version indicates the language version used by the code in this module
		// - the minimum version of CUE required to evaluate the code in this
		// module. When a later version of CUE is evaluating code in this module,
		// this will be used to choose version-specific behavior. If an earlier
		// version of CUE is used, an error will be given.
		language?: version?: #Semver

		// source holds information about the source of the files within the
		// module. This field is mandatory at publish time.
		source?: #Source

		// description describes the purpose of this module.
		description?: string

		// deps holds dependency information for modules, keyed by module path.
		deps?: [#Module]: #Dep

		// custom holds arbitrary data intended for use by third-party tools.
		// Each field at the top level represents a tooling namespace,
		// conventionally a module or domain name. Data migrated from legacy
		// module.cue files is placed in the "legacy" namespace.
		custom?: [#Module | "legacy"]: [_]: _

		#Dep: {
			// v indicates the minimum required version of the module. This can
			// be null if the version is unknown and the module entry is only
			// present to be replaced.
			v!: #Semver | null

			// default indicates this module is used as a default in case more
			// than one major version is specified for the same module path.
			// Imports must specify the exact major version for a module path if
			// there is more than one major version for that path and default is
			// not set for exactly one of them.
			default?: bool
		}

		// #Module constrains a module path. The major version indicator is
		// optional, but should always be present in a normalized module.cue
		// file.
		#Module: string

		// #Semver constrains a semantic version.
		#Semver: =~"."
	}

	// #Strict can be unified with the top level schema to enforce the strict version
	// of the schema required by the registry.
	#Strict: #File & {
		// This regular expression is taken from https://semver.org/spec/v2.0.0.html
		#Semver: =~#"^v(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+(?P<buildmetadata>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$"#

		#Module: =~#"^[^@]+(@v(0|[1-9]\d*))$"#

		// The module declaration is required.
		module!: #Module

		// No null versions, because no replacements yet.
		#Dep: v!: #Semver
	}

	// #Source describes a source of truth for a module's content.
	#Source: {
		// kind specifies the kind of source.
		//
		// The special value "self" signifies a module is stand-alone, associated
		// with no particular source. The module's file list is determined from
		// the contents of the directory (and its subdirectories) that contains
		// the cue.mod directory.
		//
		// See https://cuelang.org/docs/reference/modules/#determining-zip-file-contents
		// for details on all the possible values for kind, and how they relate
		// to determining the list of files in a module.
		kind!: "self" | "git"

		// TODO support for other VCSs:
		// kind!: "self" | "git" | "bzr" | "hg" | "svn"
	}
}

// The //error comments are specially recognized by the parsing
// code so we can avoid opaque conflict errors.
// TODO use error function when that's available.
//
// Note: we're using 1&2 rather than _|_ because
// use of _|_ causes the source location of the errors
// to be lost. See https://github.com/cue-lang/cue/issues/2319.

//error: source field is not allowed at this language version; need at least v0.9.0-alpha.0
let _errorSourceFieldRequiredVersion = 1 & 2