package app

import (
	"context"
	"os"
	"strings"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/config"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/promptexec"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
)

// PromptInspectionRequest contains the non-executing inputs required to
// validate one report's configured prompt and profile.
type PromptInspectionRequest struct {
	Resolved  report.Resolved
	Executor  promptexec.Executor
	Promptkit config.PromptkitConfig
	LookupEnv func(string) (string, bool)
}

// PromptInspectionResult contains only safe identity and provenance from a
// prompt/profile inspection.
type PromptInspectionResult struct {
	PromptID      string
	PromptVersion string
	PromptHash    string
	ProfileID     string
	BackendID     string
	ModelName     string
}

// InspectPromptExecution validates the exact prompt and profile needed for a
// report before collection, execution, or durable writes begin.
func InspectPromptExecution(ctx context.Context, req PromptInspectionRequest) (PromptInspectionResult, error) {
	if req.Executor == nil {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "prompt executor is required", nil)
	}
	definition := req.Resolved.Definition
	if strings.TrimSpace(definition.PromptID) == "" || strings.TrimSpace(definition.PromptVersion) == "" {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "report prompt identity is incomplete", nil)
	}
	inspection, err := req.Executor.InspectPrompt(ctx, definition.PromptID, definition.PromptVersion)
	if err != nil {
		return PromptInspectionResult{}, promptInspectionError("prompt inspection failed", err)
	}
	if inspection.PromptID != definition.PromptID || inspection.PromptVersion != definition.PromptVersion {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "prompt inspection did not return the requested prompt version", nil)
	}
	if !validPromptInput(inspection.Inputs) {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "prompt must declare exactly one required application/yaml data_package input", nil)
	}
	if !validPromptOutput(definition, inspection.Output) {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "prompt must declare the report JSON Schema output contract", nil)
	}
	profileID := req.Promptkit.Profile
	if profileID == "" {
		profileID = inspection.DefaultProfileID
	}
	if strings.TrimSpace(profileID) == "" {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "prompt has no execution profile", nil)
	}
	profile, err := req.Executor.InspectProfile(ctx, profileID)
	if err != nil {
		return PromptInspectionResult{}, promptInspectionError("profile inspection failed", err)
	}
	if profile.ProfileID != profileID {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.InvalidConfiguration, "profile inspection did not return the selected profile", nil)
	}
	if profile.CredentialRequired {
		return PromptInspectionResult{}, promptexec.NewError(promptexec.MissingCredential, "selected profile requires an unsupported direct API key", nil)
	}
	if strings.TrimSpace(profile.APIKeyEnv) != "" {
		lookupEnv := req.LookupEnv
		if lookupEnv == nil {
			lookupEnv = os.LookupEnv
		}
		value, present := lookupEnv(profile.APIKeyEnv)
		if !present || strings.TrimSpace(value) == "" {
			return PromptInspectionResult{}, promptexec.NewError(promptexec.MissingCredential, "selected profile credential is unavailable", nil)
		}
	}
	return PromptInspectionResult{
		PromptID:      inspection.PromptID,
		PromptVersion: inspection.PromptVersion,
		PromptHash:    inspection.PromptHash,
		ProfileID:     profile.ProfileID,
		BackendID:     profile.BackendID,
		ModelName:     profile.ModelName,
	}, nil
}

func validPromptInput(inputs []promptexec.InputDefinition) bool {
	return len(inputs) == 1 && inputs[0].Name == "data_package" && inputs[0].Required && inputs[0].ContentType == "application/yaml"
}

func validPromptOutput(definition report.Definition, output promptexec.OutputContract) bool {
	return output.Format == "json" && output.ValidationMode == "json_schema" && output.SchemaPath == definition.GeneratedTextSchemaID+".generated_text.schema.json"
}

func promptInspectionError(operation string, err error) error {
	if promptexec.CategoryOf(err) != "" {
		return err
	}
	return promptexec.NewError(promptexec.InvalidConfiguration, operation, err)
}