package llm

import (
	"context"
	"errors"
	"fmt"
	"io/fs"
	"net/http"
	"path/filepath"
	"strings"
	"sync/atomic"

	"gitea.maximumdirect.net/eric/audita/v3/internal/core/config"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/responseschema"
	"gitea.maximumdirect.net/eric/audita/v3/internal/prompts"
	ck "go.maximumdirect.net/configkit"
	pk "go.maximumdirect.net/promptkit"
)

// Runtime owns the captured engine shared by all processing clients.
type Runtime struct {
	Config      config.Config
	Engine      *pk.Engine
	SourcePaths []string
	nextCallID  atomic.Uint64
}

type AssetError struct{ Err error }

func (e *AssetError) Error() string { return e.Err.Error() }
func (e *AssetError) Unwrap() error { return e.Err }

const operatorImports = `config:
  imports:
    - path: prompts.yml
      required: false
    - dir: prompts
      required: false
      recursive: true
      pattern: ["*.yml", "*.yaml"]
`

func NewRuntime(ctx context.Context, loaded *ck.Result[config.Config], client *http.Client) (*Runtime, error) {
	return newRuntimeWithPromptFS(ctx, loaded, client, prompts.Filesystem())
}

func newRuntimeWithPromptFS(ctx context.Context, loaded *ck.Result[config.Config], client *http.Client, promptFS fs.FS) (*Runtime, error) {
	if err := ctx.Err(); err != nil {
		return nil, err
	}
	if loaded == nil {
		return nil, fmt.Errorf("application configuration is required")
	}
	embedded, err := pk.FilesystemInputs("Audita embedded prompts", promptFS, prompts.AssetRoot)
	if err != nil {
		return nil, &AssetError{Err: fmt.Errorf("discover embedded prompts: %w", err)}
	}
	sources := pk.ConfigurationSources{Underlays: []ck.Underlay{{Inputs: embedded}}}
	for _, source := range loaded.Sources() {
		if source.Layer != ck.LayerMain || source.ImportedFrom != nil {
			continue
		}
		context, ok := loaded.SourceContext(source.ID)
		if !ok {
			break
		}
		var filesystemContext ck.FilesystemContext
		if source.Kind == ck.SourceKindFile && source.Path != "" {
			base := filepath.Dir(source.Path)
			root := base
			if context.BaseDir != "." {
				for range strings.Split(context.BaseDir, "/") {
					root = filepath.Dir(root)
				}
			}
			filesystemContext = ck.FilesystemContext{Root: root, BaseDir: base}
		} else {
			filesystem := ck.NewFilesystem("Audita operator prompts", context.FS)
			filesystemContext = ck.FilesystemContext{FS: &filesystem, Root: ".", BaseDir: context.BaseDir}
		}
		sources.Underlays = append(sources.Underlays, ck.Underlay{Inputs: []ck.Input{{
			Source: ck.Bytes("Audita automatic prompt imports", []byte(operatorImports)), Imports: true,
			Filesystem: &filesystemContext,
		}}})
		break
	}
	engine, err := pk.NewEngine(pk.Config{Sources: sources, HTTPClient: client}, pk.WithSchemaFS(responseschema.Filesystem(), responseschema.AssetRoot))
	if err != nil {
		return nil, embeddedAssetOrInputError(ctx, embedded, fmt.Errorf("assemble LLM runtime: %w", err))
	}
	for _, meta := range prompts.RegisteredMetadata() {
		if _, err := engine.InspectPrompt(ctx, meta.PromptID); err != nil {
			return nil, embeddedAssetOrInputError(ctx, embedded, fmt.Errorf("inspect prompt %s: %w", meta.PromptID, err))
		}
	}
	paths, err := capturedSourcePaths(engine)
	if err != nil {
		return nil, fmt.Errorf("inspect captured LLM sources: %w", err)
	}
	return &Runtime{Config: loaded.Config, Engine: engine, SourcePaths: paths}, nil
}

func embeddedAssetOrInputError(ctx context.Context, inputs []ck.Input, cause error) error {
	if err := ctx.Err(); err != nil {
		return err
	}
	engine, err := pk.NewEngine(pk.Config{Sources: pk.ConfigurationSources{Underlays: []ck.Underlay{{Inputs: inputs}}}}, pk.WithSchemaFS(responseschema.Filesystem(), responseschema.AssetRoot))
	if err == nil {
		for _, meta := range prompts.RegisteredMetadata() {
			if _, err = engine.InspectPrompt(ctx, meta.PromptID); err != nil {
				break
			}
		}
	}
	if err := ctx.Err(); err != nil {
		return err
	}
	if err != nil {
		return &AssetError{Err: fmt.Errorf("validate embedded prompt assets: %w", err)}
	}
	return cause
}

func IsAssetError(err error) bool { var target *AssetError; return errors.As(err, &target) }