package publish

import (
	"context"
	"fmt"

	"gitea.maximumdirect.net/eric/distributor/internal/state"
	"gitea.maximumdirect.net/eric/distributor/internal/storage"
	"gitea.maximumdirect.net/eric/distributor/internal/transform"
)

func PlanOutputs(ctx context.Context, req Request) ([]Output, error) {
	var outputs []Output
	if req.Publish.Source {
		sourceOutputs, err := PlanSourceOutputs(req)
		if err != nil {
			return nil, err
		}
		outputs = append(outputs, sourceOutputs...)
	}
	if req.Publish.HTML {
		transformer, err := resolveTransformer(req.Transformers, transform.MarkdownToHTML)
		if err != nil {
			return nil, err
		}
		generatedOutputs, err := transformer.Generate(ctx, transform.Request{
			SourceBundle:  req.SourceBundle,
			SourceBackend: req.SourceBackend,
			Markdown: transform.MarkdownOptions{
				Mode:  req.Transform.MarkdownToHTML.Mode,
				Input: req.Transform.MarkdownToHTML.Input,
			},
		})
		if err != nil {
			return nil, err
		}
		if len(generatedOutputs) == 0 {
			return nil, fmt.Errorf("publish html requested but no markdown source files were found")
		}
		for _, generated := range generatedOutputs {
			outputs = append(outputs, Output{
				SourcePath:      generated.SourcePath,
				DestinationPath: generated.Path,
				Kind:            state.OutputKindGenerated,
				Transform:       generated.Transform,
				Data:            generated.Data,
				SHA256:          generated.SHA256,
				Size:            generated.Size,
			})
		}
	}
	if err := rejectOutputCollisions(outputs); err != nil {
		return nil, err
	}
	return outputs, nil
}

func resolveTransformer(resolver TransformerResolver, name string) (transform.Transformer, error) {
	if resolver == nil {
		return nil, fmt.Errorf("transformer resolver is required for %s", name)
	}
	transformer, ok := resolver.Get(name)
	if !ok {
		return nil, fmt.Errorf("transformer %s is not registered", name)
	}
	return transformer, nil
}

func PlanSourceOutputs(req Request) ([]Output, error) {
	outputs := make([]Output, 0, len(req.SourceBundle.Manifest.Files))
	for _, file := range req.SourceBundle.Manifest.Files {
		if err := storage.ValidatePath(file.Path); err != nil {
			return nil, fmt.Errorf("destination output path %q: %w", file.Path, err)
		}
		outputs = append(outputs, Output{
			SourcePath:      file.Path,
			DestinationPath: file.Path,
			Kind:            state.OutputKindSource,
			SHA256:          file.SHA256,
			Size:            file.Size,
		})
	}
	return outputs, nil
}

func rejectOutputCollisions(outputs []Output) error {
	seen := make(map[string]struct{}, len(outputs))
	for _, output := range outputs {
		if err := storage.ValidatePath(output.DestinationPath); err != nil {
			return fmt.Errorf("destination output path %q: %w", output.DestinationPath, err)
		}
		if _, exists := seen[output.DestinationPath]; exists {
			return fmt.Errorf("destination output path collision: %s", output.DestinationPath)
		}
		seen[output.DestinationPath] = struct{}{}
	}
	return nil
}

func (o Output) StateOutputFile() state.OutputFile {
	return state.OutputFile{
		Path:       o.DestinationPath,
		Kind:       o.Kind,
		SourcePath: o.SourcePath,
		Transform:  o.Transform,
		URL:        o.URL,
		SHA256:     o.SHA256,
		Size:       o.Size,
	}
}

func (o Output) ManagedPath() string {
	return o.DestinationPath
}

func StateOutputFiles(outputs []Output) []state.OutputFile {
	files := make([]state.OutputFile, 0, len(outputs))
	for _, output := range outputs {
		files = append(files, output.StateOutputFile())
	}
	return files
}

func ManagedOutputPaths(outputs []Output) []string {
	paths := make([]string, 0, len(outputs))
	for _, output := range outputs {
		paths = append(paths, output.ManagedPath())
	}
	return paths
}

func stateOutputManagedPaths(outputs []state.OutputFile) []string {
	paths := make([]string, 0, len(outputs))
	for _, output := range outputs {
		paths = append(paths, output.Path)
	}
	return paths
}