package ckprompt

import (
	"context"
	"errors"
	"fmt"
	"io"
	"strconv"

	commandkit "gitea.maximumdirect.net/eric/CommandKit"
	"gitea.maximumdirect.net/eric/CommandKit/integrations/ckconfig"
	configkit "gitea.maximumdirect.net/eric/ConfigKit"
	promptkit "gitea.maximumdirect.net/eric/promptkit"
)

// PromptRequest selects one named prompt for inspection.
type PromptRequest struct {
	// Selection carries the configuration and overlay values supplied to the command.
	Selection ckconfig.Selection
	// ID is the selected named prompt.
	ID string
}

// ProfileRequest selects one named profile for inspection.
type ProfileRequest struct {
	// Selection carries the configuration and overlay values supplied to the command.
	Selection ckconfig.Selection
	// ID is the selected named profile.
	ID string
}

// CatalogRequest selects the configuration and native namespace filter for a
// prompt, profile, or backend catalog operation. A zero Filter preserves
// PromptKit's native default selection.
type CatalogRequest struct {
	// Selection carries the configuration and overlay supplied to the command.
	Selection ckconfig.Selection
	// Filter is forwarded unchanged to each filterable native catalog. Its zero
	// value preserves PromptKit's default namespace selection.
	Filter promptkit.NamespaceFilter
}

// NamespaceRequest selects the configuration and native resource kinds for a
// namespace catalog operation. An empty Kinds slice preserves PromptKit's
// native default selection.
type NamespaceRequest struct {
	// Selection carries the configuration and overlay supplied to the command.
	Selection ckconfig.Selection
	// Kinds is forwarded unchanged to the native namespace catalog. An empty
	// slice preserves PromptKit's default kind selection.
	Kinds []promptkit.ResourceKind
}

// RequirementsRequest selects a prompt context for native requirements
// inspection.
type RequirementsRequest struct {
	// Selection carries the configuration and overlay values supplied to the command.
	Selection ckconfig.Selection
	// Inspection forwards PromptKit's native prompt, version, profile, variable,
	// and session discovery context. Optional version, profile, and session
	// strings retain PromptKit's empty-value semantics.
	Inspection promptkit.RequirementInspectionRequest
}

// Suite describes application-owned input, shared state, and optional catalog,
// named inspection, requirements discovery, concrete request validation, and
// smoke testing capabilities. Its private issues retain adapter construction
// failures.
// Factory results and callback effects remain caller-owned: Command does not
// deep-copy arbitrary objects or repair aliases returned by factories.
// A reached operation prepares one input, applies its captured selectors, and
// checks the input before creating state and calling the selected provider.
// Factories are not invoked during construction, installation, help, or version,
// and need not run after failure.
type Suite[I, S any] struct {
	// NewInput is called once when inspection, requirements, validation, smoke,
	// or catalog input preparation is reached, before applying selectors and
	// calling CheckInput.
	// If nil, input is the zero value of I, including nil for pointer types.
	NewInput func() I
	// NewState is called once when an inspection, validation, smoke, or catalog
	// callback is reached, after input checks pass. If nil, state is the zero
	// value of S, including nil for pointer types.
	NewState func() S
	// Selectors declares the original typed flags accepted by inspection,
	// requirements, validation, smoke, and catalog commands.
	Selectors []commandkit.Flag[I]
	// CheckInput validates selected inspection, requirements, validation, smoke,
	// or catalog input before state creation.
	CheckInput func(ckconfig.Selection, I) error
	// InspectPrompt inspects the selected prompt after input and state
	// preparation. Its acquisition carries independent loader diagnostics and
	// terminal context alongside any native inspection result.
	InspectPrompt func(context.Context, PromptRequest, I, S) (commandkit.Acquired[*promptkit.PromptInspection], error)
	// InspectProfile inspects the selected profile after input and state
	// preparation. Its acquisition carries independent loader diagnostics and
	// terminal context alongside any native inspection result.
	InspectProfile func(context.Context, ProfileRequest, I, S) (commandkit.Acquired[*promptkit.ProfileInspection], error)
	// InspectRequirements inspects native PromptKit requirements after input and
	// state preparation. Its acquisition carries independent loader diagnostics
	// and terminal context alongside any native inspection result. It is
	// optional; a nil callback omits `promptkit requirements show` without
	// disabling validation or other capabilities.
	InspectRequirements func(context.Context, RequirementsRequest, I, S) (commandkit.Acquired[*promptkit.RequirementInspection], error)
	// ValidateRequest validates a concrete PromptKit request after input and
	// state preparation. It is optional; a nil callback omits
	// `promptkit requirements validate` without disabling discovery or other
	// capabilities. The acquisition carries independent diagnostics, terminal
	// context, and an empty value on success; PromptKit errors are returned
	// unchanged where supported.
	ValidateRequest func(context.Context, ValidationRequest, I, S) (commandkit.Acquired[struct{}], error)
	// SmokeTest runs one concrete native smoke-test operation after input and
	// state preparation. It is optional; nil omits only the smoke-test command.
	// The acquisition retains a native report, independent diagnostics, and
	// terminal context even when the callback also returns an error. For
	// `test all`, CommandKit calls the captured callback sequentially for each
	// selected kind after preparing input and state once.
	SmokeTest func(context.Context, SmokeRequest, I, S) (commandkit.Acquired[*promptkit.SmokeTestReport], error)
	// ListPrompts lists prompt identities after input and state preparation.
	// It is optional independently of the other catalogs; nil omits only this
	// catalog command.
	ListPrompts func(context.Context, CatalogRequest, I, S) (commandkit.Acquired[[]promptkit.PromptIdentity], error)
	// ListProfiles lists profile IDs after input and state preparation. It is
	// optional independently of the other catalogs; nil omits only this catalog
	// command.
	ListProfiles func(context.Context, CatalogRequest, I, S) (commandkit.Acquired[[]string], error)
	// ListBackends lists backend IDs after input and state preparation. It is
	// optional independently of the other catalogs; nil omits only this catalog
	// command.
	ListBackends func(context.Context, CatalogRequest, I, S) (commandkit.Acquired[[]string], error)
	// ListNamespaces lists native namespace names after input and state
	// preparation. It is optional independently of the other catalogs; nil omits
	// only this catalog command.
	ListNamespaces func(context.Context, NamespaceRequest, I, S) (commandkit.Acquired[[]string], error)
	// ListCollections lists collection information after input and state
	// preparation. It is optional independently of the other catalogs; nil
	// omits only this catalog command.
	ListCollections func(context.Context, ckconfig.Selection, I, S) (commandkit.Acquired[[]promptkit.CollectionInfo], error)

	issues []error
}

// WithRequestValidation attaches PromptKit-backed concrete request validation
// to suite while preserving its other capabilities and retained issues. Those
// issues remain attached if capabilities are narrowed before Command captures
// the suite. The
// builder, when present, runs before the engine loader and receives the seed,
// input, state, and invocation context. Its returned request is passed to
// PromptKit unchanged; the loader receives the seed's original configuration
// selection. A nil builder forwards the seed request unchanged. A builder
// failure prevents engine loading and preserves its supported error identity.
// Native validation errors supply terminal explanations and are returned with
// supported identity, and
// configuration diagnostics and terminal context from engine loading remain
// separate in the acquisition. A nil loader is retained as a suite wiring
// issue and does not install a validation callback. Callback references and
// objects remain caller-owned.
func WithRequestValidation[I, S any](
	suite Suite[I, S],
	load func(context.Context, ckconfig.Selection, I, S) (*promptkit.Engine, error),
	build func(context.Context, ValidationRequest, I, S) (promptkit.RunRequest, error),
) Suite[I, S] {
	if load == nil {
		issues := append([]error(nil), suite.issues...)
		suite.issues = append(issues, errors.New("PromptKit engine loader is nil"))
		return suite
	}

	suite.ValidateRequest = func(ctx context.Context, request ValidationRequest, input I, state S) (commandkit.Acquired[struct{}], error) {
		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[struct{}]{}, fmt.Errorf("PromptKit request validation before building: %w", err)
		}

		concreteRequest := request.Request
		if build != nil {
			built, err := build(ctx, request, input, state)
			if err != nil {
				return commandkit.Acquired[struct{}]{}, err
			}
			concreteRequest = built
		}

		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[struct{}]{}, fmt.Errorf("PromptKit request validation after building: %w", err)
		}

		engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
		if err != nil {
			return commandkit.Acquired[struct{}]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		}
		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[struct{}]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit request validation before native validation: %w", err)
		}

		if err := engine.ValidateRequest(ctx, concreteRequest); err != nil {
			messages = messages.withOperationError(err)
			return commandkit.Acquired[struct{}]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		}
		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[struct{}]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit request validation after native validation: %w", err)
		}
		return commandkit.Acquired[struct{}]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, nil
	}
	return suite
}

type engineLoader[I, S any] func(context.Context, ckconfig.Selection, I, S) (*promptkit.Engine, error)

type promptKitAcquisition struct {
	diagnostics []commandkit.Diagnostic
	explanation commandkit.Explanation
}

// withOperationError deliberately presents a native PromptKit operation error.
// Loader and request-builder errors remain application-owned. Native structured
// context takes precedence when an acquisition already supplies it.
func (messages promptKitAcquisition) withOperationError(err error) promptKitAcquisition {
	if err == nil || messages.explanation.Message != "" {
		return messages
	}
	for _, detail := range messages.explanation.Details {
		if detail != nil {
			return messages
		}
	}
	messages.explanation.Message = err.Error()
	return messages
}

// ConfigScope adapts PromptKit's captured configuration inspection to the
// standard configuration commands, including native comparison when the scope
// declares Diff. The loader is not called during declaration construction or
// installation; it is called only when a config operation selects the
// promptkit scope, with that operation's input and shared state. PromptKit
// independent diagnostics, terminal context, and supported error identity are
// returned through ckconfig's acquisition and comparison contracts.
func ConfigScope[I, S any](load func(context.Context, ckconfig.Selection, I, S) (*promptkit.Engine, error)) ckconfig.Scope[I, S] {
	scope := ckconfig.Scope[I, S]{
		Name:       "promptkit",
		Summary:    "PromptKit engine configuration.",
		Operations: []ckconfig.Operation{ckconfig.Validate, ckconfig.Show, ckconfig.Sources, ckconfig.Explain, ckconfig.Diff},
	}
	if load == nil {
		return ckconfig.WithScopeError(scope, errors.New("PromptKit configuration loader is nil"))
	}

	scope.Acquire = func(ctx context.Context, request ckconfig.Request, input I, state S) (commandkit.Acquired[ckconfig.View], error) {
		_, inspection, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
		if err != nil {
			return commandkit.Acquired[ckconfig.View]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		}
		return commandkit.Acquired[ckconfig.View]{
			Value: ckconfig.View{
				Effective:   inspection,
				Sources:     inspection,
				Explanation: inspection,
			},
			Diagnostics: messages.diagnostics,
			Explanation: messages.explanation,
		}, nil
	}
	scope.Compare = func(ctx context.Context, request ckconfig.ComparisonRequest[I], state S) (commandkit.Acquired[[]configkit.Difference], error) {
		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[[]configkit.Difference]{}, fmt.Errorf("PromptKit scope %q comparison before left load: %w", scope.Name, err)
		}

		_, leftInspection, messages, err := loadPromptKitEngine(ctx, request.Left.Selection, request.Left.Input, state, "left", load)
		if err != nil {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit scope %q left comparison load: %w", scope.Name, err)
		}

		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit scope %q comparison after left load: %w", scope.Name, err)
		}

		_, rightInspection, rightMessages, err := loadPromptKitEngine(ctx, request.Right.Selection, request.Right.Input, state, "right", load)
		messages = appendPromptKitAcquisition(messages, rightMessages)
		if err != nil {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit scope %q right comparison load: %w", scope.Name, err)
		}

		if err := promptKitContextError(ctx); err != nil {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit scope %q comparison before native diff: %w", scope.Name, err)
		}

		differences, err := leftInspection.Diff(rightInspection)
		messages = messages.withOperationError(err)
		if err != nil {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, fmt.Errorf("PromptKit scope %q native configuration diff: %w", scope.Name, err)
		}
		return commandkit.Acquired[[]configkit.Difference]{Value: differences, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, nil
	}
	return scope
}

func promptKitContextError(ctx context.Context) error {
	if ctx == nil {
		return nil
	}
	return ctx.Err()
}

// FromEngine supplies eight PromptKit-backed callbacks: prompt, profile,
// backend, namespace, and collection catalogs, plus named prompt and profile
// inspection and requirements discovery.
// The requirements callback forwards RequirementsRequest.Inspection to
// Engine.InspectRequirements. Concrete request validation is an independent
// capability and can be composed explicitly with WithRequestValidation. Smoke
// testing is also an explicit capability installed with WithSmokeTesting.
// FromEngine does not call the loader during construction. Each selected
// operation passes its context, supplied selection, initialized input, and
// shared invocation state to the loader before calling PromptKit's public
// listing or inspection method. Applications can narrow, wrap, or replace these
// callbacks before Command captures them. A nil loader is retained as an
// adapter issue. Each callback returns independent loader diagnostics and
// terminal context alongside the native operation's value and error. Native
// operation errors supply terminal explanations when structured context is absent.
func FromEngine[I, S any](load func(context.Context, ckconfig.Selection, I, S) (*promptkit.Engine, error)) Suite[I, S] {
	if load == nil {
		return Suite[I, S]{issues: []error{errors.New("PromptKit engine loader is nil")}}
	}

	return Suite[I, S]{
		ListPrompts: func(ctx context.Context, request CatalogRequest, input I, state S) (commandkit.Acquired[[]promptkit.PromptIdentity], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[[]promptkit.PromptIdentity]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			prompts, err := engine.ListPrompts(ctx, request.Filter)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[[]promptkit.PromptIdentity]{Value: prompts, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		ListProfiles: func(ctx context.Context, request CatalogRequest, input I, state S) (commandkit.Acquired[[]string], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[[]string]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			profiles, err := engine.ListProfiles(ctx, request.Filter)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[[]string]{Value: profiles, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		ListBackends: func(ctx context.Context, request CatalogRequest, input I, state S) (commandkit.Acquired[[]string], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[[]string]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			backends, err := engine.ListBackends(ctx, request.Filter)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[[]string]{Value: backends, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		ListNamespaces: func(ctx context.Context, request NamespaceRequest, input I, state S) (commandkit.Acquired[[]string], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[[]string]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			namespaces, err := engine.ListNamespaces(ctx, request.Kinds...)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[[]string]{Value: namespaces, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		ListCollections: func(ctx context.Context, selection ckconfig.Selection, input I, state S) (commandkit.Acquired[[]promptkit.CollectionInfo], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[[]promptkit.CollectionInfo]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			collections, err := engine.ListCollections(ctx)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[[]promptkit.CollectionInfo]{Value: collections, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		InspectPrompt: func(ctx context.Context, request PromptRequest, input I, state S) (commandkit.Acquired[*promptkit.PromptInspection], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[*promptkit.PromptInspection]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			inspection, err := engine.InspectPrompt(ctx, request.ID)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[*promptkit.PromptInspection]{Value: inspection, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		InspectProfile: func(ctx context.Context, request ProfileRequest, input I, state S) (commandkit.Acquired[*promptkit.ProfileInspection], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[*promptkit.ProfileInspection]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			inspection, err := engine.InspectProfile(ctx, request.ID)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[*promptkit.ProfileInspection]{Value: inspection, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
		InspectRequirements: func(ctx context.Context, request RequirementsRequest, input I, state S) (commandkit.Acquired[*promptkit.RequirementInspection], error) {
			engine, _, messages, err := loadPromptKitEngine(ctx, request.Selection, input, state, "", load)
			if err != nil {
				return commandkit.Acquired[*promptkit.RequirementInspection]{Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
			}
			inspection, err := engine.InspectRequirements(ctx, request.Inspection)
			messages = messages.withOperationError(err)
			return commandkit.Acquired[*promptkit.RequirementInspection]{Value: inspection, Diagnostics: messages.diagnostics, Explanation: messages.explanation}, err
		},
	}
}

func loadPromptKitEngine[I, S any](
	ctx context.Context,
	selection ckconfig.Selection,
	input I,
	state S,
	side string,
	load engineLoader[I, S],
) (*promptkit.Engine, promptkit.ConfigurationInspection, promptKitAcquisition, error) {
	engine, err := load(ctx, selection, input, state)
	if err != nil {
		var loadErr *configkit.LoadError
		if errors.As(err, &loadErr) {
			messages := promptKitDiagnostics("promptkit", side, loadErr.Sources(), loadErr.Diagnostics())
			return nil, promptkit.ConfigurationInspection{}, messages, err
		}
		return nil, promptkit.ConfigurationInspection{}, promptKitAcquisition{}, err
	}
	if engine == nil {
		return nil, promptkit.ConfigurationInspection{}, promptKitAcquisition{}, errors.New("PromptKit configuration loader returned a nil engine")
	}
	inspection, err := engine.InspectConfiguration()
	messages := promptKitDiagnostics("promptkit", side, inspection.Sources(), inspection.Diagnostics())
	messages = messages.withOperationError(err)
	if err != nil {
		return nil, inspection, messages, err
	}
	if ctx != nil {
		if err := ctx.Err(); err != nil {
			return nil, promptkit.ConfigurationInspection{}, messages, err
		}
	}
	return engine, inspection, messages, nil
}

func appendPromptKitAcquisition(left, right promptKitAcquisition) promptKitAcquisition {
	left.diagnostics = append(left.diagnostics, right.diagnostics...)
	left.explanation.Details = append(left.explanation.Details, right.explanation.Details...)
	if left.explanation.Message == "" {
		left.explanation.Message = right.explanation.Message
	}
	return left
}

func promptKitDiagnostics(scope, side string, sources []configkit.SourceInfo, records []configkit.Diagnostic) promptKitAcquisition {
	if len(records) == 0 {
		return promptKitAcquisition{}
	}
	// Snapshot provider-owned slices before deferring their report to invocation.
	sources = append([]configkit.SourceInfo(nil), sources...)
	records = append([]configkit.Diagnostic(nil), records...)
	for index := range records {
		if records[index].Primary != nil {
			primary := *records[index].Primary
			records[index].Primary = &primary
		}
		records[index].Related = append([]configkit.Location(nil), records[index].Related...)
	}
	var warnings, failures []configkit.Diagnostic
	for _, record := range records {
		if record.Severity == configkit.SeverityError {
			failures = append(failures, record)
		} else {
			warnings = append(warnings, record)
		}
	}
	messages := promptKitAcquisition{}
	if len(warnings) > 0 {
		messages.diagnostics = []commandkit.Diagnostic{{
			Severity: commandkit.SeverityWarning,
			Write: func(writer io.Writer) error {
				return writePromptKitDiagnostics(writer, scope, side, sources, warnings)
			},
		}}
	}
	if len(failures) > 0 {
		messages.explanation = commandkit.Explanation{Details: []commandkit.Detail{func(writer io.Writer) error {
			return writePromptKitDiagnostics(writer, scope, side, sources, failures)
		}}}
	}
	return messages
}

func writePromptKitDiagnostics(writer io.Writer, scope, side string, sources []configkit.SourceInfo, records []configkit.Diagnostic) error {
	heading := "Configuration scope " + strconv.Quote(scope)
	if side != "" {
		heading += " (" + side + ")"
	}
	if _, err := fmt.Fprintf(writer, "%s:\n", heading); err != nil {
		return err
	}
	if len(sources) > 0 {
		if _, err := io.WriteString(writer, "Source IDs:\n"); err != nil {
			return err
		}
		for _, source := range sources {
			if _, err := fmt.Fprintf(writer, "  %s: label=%s, path=%s\n", strconv.Quote(source.ID), strconv.Quote(source.Label), strconv.Quote(source.Path)); err != nil {
				return err
			}
		}
	}
	return configkit.WriteDiagnostics(writer, records)
}