package seriatim

import (
	"context"
	"fmt"

	"gitea.maximumdirect.net/eric/narratio/internal/adapters/subprocess"
)

// NoopRunner is a deterministic no-op seriatim adapter.
type NoopRunner struct{}

// Run returns the requested output path with placeholder metadata.
func (n *NoopRunner) Run(ctx context.Context, req MergeRequest) (MergeResult, error) {
	if err := ctx.Err(); err != nil {
		return MergeResult{}, err
	}
	if err := materializePlaceholders(req); err != nil {
		return MergeResult{}, err
	}
	return MergeResult{
		MergedTranscriptPath: req.OutputMergedTranscriptPath,
		ReportPath:           req.ReportPath,
		StdoutLogPath:        req.StdoutLogPath,
		StderrLogPath:        req.StderrLogPath,
		GeneratedConfigPath:  req.GeneratedConfigPath,
		InvokedBinary:        "noop",
		Metadata:             map[string]any{"placeholder": true},
	}, nil
}

// FakeRunner captures merge requests and returns deterministic responses.
type FakeRunner struct {
	Requests []MergeRequest
	Err      error
	Result   MergeResult
}

// Run records request and returns configured response.
func (f *FakeRunner) Run(ctx context.Context, req MergeRequest) (MergeResult, error) {
	if err := ctx.Err(); err != nil {
		return MergeResult{}, err
	}
	f.Requests = append(f.Requests, req)
	if f.Err != nil {
		return MergeResult{}, f.Err
	}
	if err := materializePlaceholders(req); err != nil {
		return MergeResult{}, err
	}
	res := f.Result
	if res.MergedTranscriptPath == "" {
		res.MergedTranscriptPath = req.OutputMergedTranscriptPath
	}
	if res.ReportPath == "" {
		res.ReportPath = req.ReportPath
	}
	if res.StdoutLogPath == "" {
		res.StdoutLogPath = req.StdoutLogPath
	}
	if res.StderrLogPath == "" {
		res.StderrLogPath = req.StderrLogPath
	}
	if res.GeneratedConfigPath == "" {
		res.GeneratedConfigPath = req.GeneratedConfigPath
	}
	if res.InvokedBinary == "" {
		res.InvokedBinary = "fake"
	}
	if res.Metadata == nil {
		res.Metadata = map[string]any{"fake": true}
	}
	return res, nil
}

func materializePlaceholders(req MergeRequest) error {
	if req.OutputMergedTranscriptPath != "" {
		if err := subprocess.WriteFileAtomic(req.OutputMergedTranscriptPath, []byte(`{"schema":"seriatim.intermediate.v1","segments":[]}`), 0o644); err != nil {
			return fmt.Errorf("write merged transcript %q: %w", req.OutputMergedTranscriptPath, err)
		}
	}
	if req.GeneratedConfigPath != "" {
		payload := map[string]any{
			"schema":                 "seriatim.generated.v1",
			"placeholder":            true,
			"input_transcript_paths": req.InputTranscriptPaths,
			"output_path":            req.OutputMergedTranscriptPath,
		}
		if err := subprocess.WriteYAMLAtomic(req.GeneratedConfigPath, payload, 0o644); err != nil {
			return fmt.Errorf("write generated config %q: %w", req.GeneratedConfigPath, err)
		}
	}
	if req.StdoutLogPath != "" {
		if err := subprocess.WriteFileAtomic(req.StdoutLogPath, []byte("seriatim noop/fake stdout placeholder\n"), 0o644); err != nil {
			return fmt.Errorf("write stdout log %q: %w", req.StdoutLogPath, err)
		}
	}
	if req.StderrLogPath != "" {
		if err := subprocess.WriteFileAtomic(req.StderrLogPath, []byte("seriatim noop/fake stderr placeholder\n"), 0o644); err != nil {
			return fmt.Errorf("write stderr log %q: %w", req.StderrLogPath, err)
		}
	}
	if req.ReportPath != "" {
		if err := subprocess.WriteFileAtomic(req.ReportPath, []byte(`{"schema":"seriatim.report.v1","placeholder":true}`), 0o644); err != nil {
			return fmt.Errorf("write report %q: %w", req.ReportPath, err)
		}
	}
	return nil
}