package drmdb

import (
	"sort"

	"git.sr.ht/~emersion/drmdb/database"
	"git.sr.ht/~emersion/drmdb/drmtree"
	"git.sr.ht/~emersion/go-drm"
	"github.com/mcuadros/go-version"
)

func walkProps(props drmtree.PropertyMap, obj drm.AnyID, f func(drm.AnyID, string, *drmtree.Property) error) error {
	for name, prop := range props {
		if err := f(obj, name, &prop); err != nil {
			return err
		}
	}
	return nil
}

func walkNodeProps(n *drmtree.Node, f func(drm.AnyID, string, *drmtree.Property) error) error {
	for _, conn := range n.Connectors {
		if err := walkProps(conn.Properties, conn.ID, f); err != nil {
			return err
		}
	}
	for _, crtc := range n.CRTCs {
		if err := walkProps(crtc.Properties, crtc.ID, f); err != nil {
			return err
		}
	}
	for _, plane := range n.Planes {
		if err := walkProps(plane.Properties, plane.ID, f); err != nil {
			return err
		}
	}
	return nil
}

func driverLess(a *drmtree.Driver, b *drmtree.Driver) bool {
	if a.Version.Less(&b.Version) {
		return true
	}
	// Linux is the upstream
	if b.Kernel.SysName == "Linux" && a.Kernel.SysName != "Linux" {
		return true
	}
	return version.Compare(a.Kernel.Release, b.Kernel.Release, "<")
}

type walkLatestField int

const (
	walkLatestDriver walkLatestField = iota
	walkLatestDevice
)

func walkLatest(db *database.DB, f walkLatestField, fn func(k string, n *drmtree.Node) error) error {
	type node struct {
		k string
		n *drmtree.Node
	}

	latest := make(map[string]node)
	err := db.Walk(func(k string, n *drmtree.Node) error {
		var latestKey string
		switch f {
		case walkLatestDriver:
			latestKey = n.Driver.Name
		case walkLatestDevice:
			latestKey = n.Device.BusID()
		}
		if latestKey == "" {
			return nil
		}

		other, ok := latest[latestKey]
		if ok && driverLess(n.Driver, other.n.Driver) {
			return nil
		}
		latest[latestKey] = node{k, n}
		return nil
	})
	if err != nil {
		return err
	}

	keys := make([]string, 0, len(latest))
	for k := range latest {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	for _, k := range keys {
		n := latest[k]
		if err := fn(n.k, n.n); err != nil {
			return err
		}
	}
	return nil
}