package publish

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

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

func Execute(ctx context.Context, req Request, plan Plan) error {
	switch plan.Action {
	case ActionSkipSame, ActionSkipDestinationNewer:
		return nil
	case ActionPublishNew, ActionReplaceOlder:
	default:
		return fmt.Errorf("cannot execute action %s: %s", plan.Action, plan.Reason)
	}

	if plan.Action == ActionReplaceOlder {
		if plan.ExistingState == nil {
			return fmt.Errorf("replace requires existing destination state")
		}
		if err := req.DestinationBackend.DeleteManagedBundle(ctx, req.DestinationBundlePath, existingManagedOutputPaths(*plan.ExistingState), storage.DeleteOptions{IgnoreMissing: true, PruneEmptyDirs: true}); err != nil {
			return err
		}
		if err := ensureDestinationEmpty(ctx, req.DestinationBackend, req.DestinationBundlePath); err != nil {
			return err
		}
	}

	writtenOutputs := make([]Output, 0, len(plan.Outputs))
	cleanup := func() {
		_ = req.DestinationBackend.DeleteManagedBundle(ctx, req.DestinationBundlePath, managedOutputPaths(writtenOutputs), storage.DeleteOptions{IgnoreMissing: true, PruneEmptyDirs: true})
	}
	for _, output := range plan.Outputs {
		destinationPath, err := storage.Join(req.DestinationBundlePath, output.DestinationPath)
		if err != nil {
			cleanup()
			return err
		}
		data := output.Data
		if output.Kind == state.OutputKindSource {
			sourcePath, err := storage.Join(req.SourceBundle.RootRelativePath, output.SourcePath)
			if err != nil {
				cleanup()
				return err
			}
			data, err = req.SourceBackend.ReadFile(ctx, sourcePath)
			if err != nil {
				cleanup()
				return err
			}
		}
		if _, err := req.DestinationBackend.WriteFile(ctx, destinationPath, data, storage.WriteOptions{Overwrite: false, PreferAtomic: true}); err != nil {
			cleanup()
			return err
		}
		writtenOutputs = append(writtenOutputs, output)
	}

	destinationState := state.DistributorState{
		SchemaVersion:      state.SchemaVersion,
		DistributorVersion: req.DistributorVersion,
		PipelineID:         req.PipelineID,
		DestinationID:      req.DestinationID,
		PublishedAt:        time.Now().UTC(),
		Source:             state.SourceState{Manifest: req.SourceBundle.Manifest},
		Outputs:            stateOutputs(plan.Outputs),
	}
	if err := state.Validate(destinationState); err != nil {
		cleanup()
		return err
	}
	data, err := json.MarshalIndent(destinationState, "", "  ")
	if err != nil {
		cleanup()
		return err
	}
	data = append(data, '\n')
	statePath, err := storage.StatePath(req.DestinationBundlePath)
	if err != nil {
		cleanup()
		return err
	}
	if _, err := req.DestinationBackend.WriteFile(ctx, statePath, data, storage.WriteOptions{Overwrite: false, PreferAtomic: true}); err != nil {
		cleanup()
		return err
	}
	return nil
}

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