// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package internal

import "sort"

// SymbolSection is the documentation section where a symbol appears.
type SymbolSection string

const (
	SymbolSectionConstants SymbolSection = "Constants"
	SymbolSectionVariables SymbolSection = "Variables"
	SymbolSectionFunctions SymbolSection = "Functions"
	SymbolSectionTypes     SymbolSection = "Types"
)

// SymbolKind is the type of a symbol.
type SymbolKind string

const (
	SymbolKindConstant SymbolKind = "Constant"
	SymbolKindVariable SymbolKind = "Variable"
	SymbolKindFunction SymbolKind = "Function"
	SymbolKindType     SymbolKind = "Type"
	SymbolKindField    SymbolKind = "Field"
	SymbolKindMethod   SymbolKind = "Method"
)

// Symbol is an element in the package API. A symbol can be a constant,
// variable, function, or type.
type Symbol struct {
	// Name is the name of the symbol.
	Name string

	// Synopsis is the one line description of the symbol as displayed
	// in the package documentation.
	Synopsis string

	// Section is the section that a symbol appears in.
	Section SymbolSection

	// Kind is the type of a symbol, which is either a constant, variable,
	// function, type, field or method.
	Kind SymbolKind

	// ParentName if name of the parent type if available, otherwise
	// the empty string. For example, the parent type for
	// net/http.FileServer is Handler.
	ParentName string

	// Children contain the child symbols for this symbol. This will
	// only be populated when the SymbolType is "Type". For example, the
	// children of net/http.Handler are FileServer, NotFoundHandler,
	// RedirectHandler, StripPrefix, and TimeoutHandler. Each child
	// symbol will have ParentName set to the Name of this type.
	Children []*Symbol

	// SinceVersion is the first version when the symbol was introduced.
	SinceVersion string

	// GOOS specifies the execution operating system where the symbol appears.
	GOOS string

	// GOARCH specifies the execution architecture where the symbol appears.
	GOARCH string
}

// UnitSymbol represents a symbol that is part of a unit.
type UnitSymbol struct {
	// TODO: factor out duplicate fields between Symbol and UnitSymbol
	Name       string
	ParentName string
	Synopsis   string
	Section    SymbolSection
	Kind       SymbolKind

	// Version is the unit version.
	Version string

	// builds are the build contexts that apply to this symbol.
	builds map[BuildContext]bool
}

// BuildContexts returns the build contexts for this UnitSymbol.
func (us *UnitSymbol) BuildContexts() []BuildContext {
	var builds []BuildContext
	for b := range us.builds {
		builds = append(builds, b)
	}
	sort.Slice(builds, func(i, j int) bool {
		return builds[i].GOOS < builds[j].GOOS
	})
	return builds
}

// AddBuildContext adds a build context supported by this UnitSymbol.
func (us *UnitSymbol) AddBuildContext(build BuildContext) {
	if us.builds == nil {
		us.builds = map[BuildContext]bool{}
	}
	if build != BuildContextAll {
		us.builds[build] = true
		return
	}
	for _, b := range BuildContexts {
		us.builds[b] = true
	}
}

// SupportsBuild reports whether the provided build is supported by this
// UnitSymbol. If the build is BuildContextAll, this is interpreted as this
// unit symbol supports at least one build context.
func (us *UnitSymbol) SupportsBuild(build BuildContext) bool {
	if build == BuildContextAll {
		return len(us.builds) > 0
	}
	return us.builds[build]
}

// InAll reports whether the unit symbol supports all build contexts.
func (us *UnitSymbol) InAll() bool {
	return len(us.builds) == len(BuildContexts)
}