package main

import (
	"errors"
	"slices"
	"strings"

	"hakurei.app/internal/pkg"
	"hakurei.app/internal/rosa"
)

const (
	declarationAscending = iota
	declarationDescending
	nameAscending
	nameDescending

	sortOrderEnd = iota - 1
)

// packageIndex refers to metadata by name and various sort orders.
type packageIndex struct {
	sorts [sortOrderEnd + 1][rosa.PresetUnexportedStart]*metadata
	names map[string]*metadata

	// Taken from [rosa.Report] if available.
	handleAccess func(*error) func()
}

// metadata holds [rosa.Metadata] extended with additional information.
type metadata struct {
	p rosa.PArtifact
	*rosa.Metadata

	// Populated via [rosa.Toolchain.Version], [rosa.Unversioned] is equivalent
	// to the zero value. Otherwise, the zero value is invalid.
	Version string `json:"version,omitempty"`
	// Output data size, available if present in report.
	Size int64 `json:"size,omitempty"`
	// Whether the underlying [pkg.Artifact] is present in the report.
	HasReport bool `json:"report"`

	// Ident string encoded ahead of time.
	ids string
	// Backed by [rosa.Report], access must be prepared by HandleAccess.
	status []byte
}

// populate deterministically populates packageIndex, optionally with a report.
func (index *packageIndex) populate(cache *pkg.Cache, report *rosa.Report) (err error) {
	if report != nil {
		defer report.HandleAccess(&err)()
		index.handleAccess = report.HandleAccess
	}

	var work [rosa.PresetUnexportedStart]*metadata
	index.names = make(map[string]*metadata)
	for p := range rosa.PresetUnexportedStart {
		m := metadata{
			p: p,

			Metadata: rosa.GetMetadata(p),
			Version:  rosa.Std.Version(p),
		}
		if m.Version == "" {
			return errors.New("invalid version from " + m.Name)
		}
		if m.Version == rosa.Unversioned {
			m.Version = ""
		}

		if cache != nil && report != nil {
			id := cache.Ident(rosa.Std.Load(p))
			m.ids = pkg.Encode(id.Value())
			m.status, m.Size = report.ArtifactOf(id)
			m.HasReport = m.Size >= 0
		}

		work[p] = &m
		index.names[m.Name] = &m
	}

	index.sorts[declarationAscending] = work
	index.sorts[declarationDescending] = work
	slices.Reverse(index.sorts[declarationDescending][:])

	index.sorts[nameAscending] = work
	slices.SortFunc(index.sorts[nameAscending][:], func(a, b *metadata) int {
		return strings.Compare(a.Name, b.Name)
	})
	index.sorts[nameDescending] = index.sorts[nameAscending]
	slices.Reverse(index.sorts[nameDescending][:])

	return
}