package state

import (
	"fmt"
	"time"
)

type OutputProjection struct {
	Path       string
	Kind       string
	SourcePath string
	Transform  string
	URL        string
	SHA256     string
	Size       int64
}

func FindOutputByPath(outputs []OutputFile, path string) (OutputFile, bool) {
	for _, output := range outputs {
		if output.Path == path {
			return output, true
		}
	}
	return OutputFile{}, false
}

func MergeOutputFiles(retained, planned []OutputFile) ([]OutputFile, error) {
	outputs := make([]OutputFile, 0, len(retained)+len(planned))
	indexByPath := make(map[string]int, len(retained)+len(planned))
	for _, output := range retained {
		if _, exists := indexByPath[output.Path]; exists {
			return nil, fmt.Errorf("state output path %q is duplicated", output.Path)
		}
		indexByPath[output.Path] = len(outputs)
		outputs = append(outputs, output)
	}
	seenPlanned := make(map[string]struct{}, len(planned))
	for _, output := range planned {
		if _, exists := seenPlanned[output.Path]; exists {
			return nil, fmt.Errorf("state output path %q is duplicated", output.Path)
		}
		seenPlanned[output.Path] = struct{}{}
		if index, exists := indexByPath[output.Path]; exists {
			outputs[index] = output
			continue
		}
		indexByPath[output.Path] = len(outputs)
		outputs = append(outputs, output)
	}
	return outputs, nil
}

func ManagedOutputPaths(s DistributorState) []string {
	paths := make([]string, 0, len(s.Outputs))
	for _, output := range s.Outputs {
		paths = append(paths, output.Path)
	}
	return paths
}

func ProjectOutputs(outputs []OutputProjection, existing []OutputFile, now time.Time) []OutputFile {
	now = now.UTC()
	files := make([]OutputFile, 0, len(outputs))
	for _, output := range outputs {
		createdAt := now
		if existingOutput, ok := FindOutputByPath(existing, output.Path); ok {
			createdAt = existingOutput.CreatedAt
		}
		files = append(files, OutputFile{
			Path:       output.Path,
			Kind:       output.Kind,
			SourcePath: output.SourcePath,
			Transform:  output.Transform,
			URL:        output.URL,
			SHA256:     output.SHA256,
			Size:       output.Size,
			CreatedAt:  createdAt,
			UpdatedAt:  now,
		})
	}
	return files
}