package domain

import (
	"errors"
	"sort"

	"git.cin.su/m/Assistant/contracts/work"
)

var (
	ErrGraphBudgetExceeded = errors.New("work graph budget exceeded")
	ErrConflictUnresolved  = errors.New("conflict resolution is not explicit")
)

func ScheduleReadyNodes(graph work.WorkGraph, active int) ([]work.GraphNodeID, error) {
	if err := ValidateWorkGraph(graph); err != nil {
		return nil, err
	}
	if active < 0 || active > graph.Budget.MaxParallel {
		return nil, ErrGraphBudgetExceeded
	}
	ready, err := ReadyGraphNodes(graph)
	if err != nil {
		return nil, err
	}
	available := graph.Budget.MaxParallel - active
	if len(ready) > available {
		ready = ready[:available]
	}
	return ready, nil
}

func AdmitGraph(graph work.WorkGraph) (work.WorkGraph, error) {
	if err := ValidateWorkGraph(graph); err != nil {
		return work.WorkGraph{}, err
	}
	for _, node := range graph.Nodes {
		if node.Attempts > graph.Budget.MaxAttempts {
			return work.WorkGraph{}, ErrGraphBudgetExceeded
		}
	}
	graph.State = work.GraphAdmitted
	return graph, nil
}

func ResolveGraphConflict(conflict work.ConflictSet, selectedCandidate string) (work.ConflictSet, error) {
	if conflict.ID == "" || conflict.GraphID == "" || conflict.GraphRevision < 1 || conflict.NodeID == "" || conflict.Resolved || selectedCandidate == "" {
		return work.ConflictSet{}, ErrConflictUnresolved
	}
	candidates := append([]string(nil), conflict.CandidateIDs...)
	sort.Strings(candidates)
	for _, candidate := range candidates {
		if candidate == selectedCandidate {
			conflict.CandidateIDs = candidates
			conflict.Resolved = true
			return conflict, nil
		}
	}
	return work.ConflictSet{}, ErrConflictUnresolved
}