package ckconfig

import (
	"fmt"
	"strings"

	commandkit "go.maximumdirect.net/commandkit"
	configkit "go.maximumdirect.net/configkit"
)

type configCommandInput[I, S any] struct {
	selection     Selection
	against       Selection
	scope         commandkit.Supplied[string]
	path          commandkit.Supplied[string]
	list          commandkit.Supplied[bool]
	historical    commandkit.Supplied[bool]
	under         commandkit.Supplied[string]
	explicit      commandkit.Supplied[bool]
	sourceID      commandkit.Supplied[string]
	details       commandkit.Supplied[bool]
	check         commandkit.Supplied[bool]
	severities    []configkit.Severity
	codes         []string
	values        commandkit.FlagValues[I]
	againstValues commandkit.FlagValues[I]
	plan          *configOperationPlan[I, S]
}

type selectedScopeInput[I, S any] struct {
	scope     *preparedScope[I, S]
	input     I
	selection Selection
}

type preparedComparison[I, S any] struct {
	scope   *preparedScope[I, S]
	request ComparisonRequest[I]
}

type configOperationPlan[I, S any] struct {
	prepared   *preparedSuite[I, S]
	operation  Operation
	scopeName  string
	path       configkit.Path
	pathSet    bool
	sourceID   commandkit.Supplied[string]
	details    bool
	check      bool
	severities []configkit.Severity
	codes      []string
	list       bool
	help       bool
	historical bool
	under      *configkit.Path
	explicit   commandkit.Supplied[bool]
	scopes     []selectedScopeInput[I, S]
	comparison *preparedComparison[I, S]
}

func newConfigOperationCommand[I, S any](prepared *preparedSuite[I, S], operation Operation) commandkit.Command {
	defaultScope := "app"
	var scopeChoices []commandkit.CompletionChoice
	allSupported := len(prepared.scopes) > 0
	for _, scope := range prepared.scopes {
		if containsOperation(scope.scope.Operations, operation) {
			scopeChoices = append(scopeChoices, commandkit.CompletionChoice{Value: scope.scope.Name})
		} else {
			allSupported = false
		}
	}
	if allSupported && (operation == Validate || operation == Show) {
		scopeChoices = append(scopeChoices, commandkit.CompletionChoice{Value: "all"})
	}
	flags := []commandkit.Flag[*configCommandInput[I, S]]{
		commandkit.ValueFlag(commandkit.FlagMeta{Name: "scope", Usage: "Configuration scope name or all where supported.", Completion: commandkit.CompleteChoices(scopeChoices...)}, &defaultScope, parseConfigString,
			func(input **configCommandInput[I, S], value commandkit.Supplied[string]) { (*input).scope = value }),
		commandkit.ValueFlag(commandkit.FlagMeta{Name: "config", Usage: "Configuration source.", Completion: commandkit.CompleteFiles()}, (*string)(nil), parseConfigString,
			func(input **configCommandInput[I, S], value commandkit.Supplied[string]) {
				(*input).selection.Config = value
			}),
		commandkit.ValueFlag(commandkit.FlagMeta{Name: "overlay", Usage: "Overlay source.", Completion: commandkit.CompleteFiles()}, (*string)(nil), parseConfigString,
			func(input **configCommandInput[I, S], value commandkit.Supplied[string]) {
				(*input).selection.Overlay = value
			}),
	}
	if operation == Diff {
		flags = append(flags,
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "details", Usage: "Show native before and after difference evidence."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).details = value }),
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "check", Usage: "Return status 3 when differences are found."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).check = value }),
			commandkit.ValueFlag(commandkit.FlagMeta{Name: "against-config", Usage: "Configuration source for the right side.", Completion: commandkit.CompleteFiles()}, (*string)(nil), parseConfigString,
				func(input **configCommandInput[I, S], value commandkit.Supplied[string]) {
					(*input).against.Config = value
				}),
			commandkit.ValueFlag(commandkit.FlagMeta{Name: "against-overlay", Usage: "Overlay source for the right side.", Completion: commandkit.CompleteFiles()}, (*string)(nil), parseConfigString,
				func(input **configCommandInput[I, S], value commandkit.Supplied[string]) {
					(*input).against.Overlay = value
				}),
		)
	}
	if operation == Validate {
		flags = append(flags,
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "details", Usage: "Show native validation findings."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).details = value }),
			commandkit.RepeatFlag(commandkit.FlagMeta{Name: "severity", Usage: "Filter detailed findings by error or warning."}, []configkit.Severity(nil), parseValidationSeverity, func(input **configCommandInput[I, S], value commandkit.Supplied[[]configkit.Severity]) {
				(*input).severities = value.Value
			}),
			commandkit.RepeatFlag(commandkit.FlagMeta{Name: "code", Usage: "Filter detailed findings by exact native code."}, []string(nil), parseConfigString, func(input **configCommandInput[I, S], value commandkit.Supplied[[]string]) {
				(*input).codes = value.Value
			}),
		)
	}
	if supportsOverrides(prepared, operation) {
		flags = append(flags, commandkit.RepeatFlag(commandkit.FlagMeta{Name: "set", Usage: "Override POINTER=JSON (pointer keys cannot contain =)."}, []configkit.Override(nil), overrideParser("--set"),
			func(input **configCommandInput[I, S], value commandkit.Supplied[[]configkit.Override]) {
				(*input).selection.Overrides = value.Value
			}))
		if operation == Diff {
			flags = append(flags, commandkit.RepeatFlag(commandkit.FlagMeta{Name: "against-set", Usage: "Right-side override POINTER=JSON (pointer keys cannot contain =)."}, []configkit.Override(nil), overrideParser("--against-set"),
				func(input **configCommandInput[I, S], value commandkit.Supplied[[]configkit.Override]) {
					(*input).against.Overrides = value.Value
				}))
		}
	}
	if operation == Explain {
		flags = append(flags,
			commandkit.ValueFlag(commandkit.FlagMeta{Name: "path", Usage: "JSON Pointer path to explain."}, (*string)(nil), parseConfigString, func(input **configCommandInput[I, S], value commandkit.Supplied[string]) { (*input).path = value }),
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "list", Usage: "List configuration paths."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).list = value }),
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "historical", Usage: "Include historical-only paths when listing."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).historical = value }),
			commandkit.ValueFlag(commandkit.FlagMeta{Name: "under", Usage: "List paths under a JSON Pointer."}, (*string)(nil), parseConfigString, func(input **configCommandInput[I, S], value commandkit.Supplied[string]) { (*input).under = value }),
			commandkit.BoolFlag(commandkit.FlagMeta{Name: "explicit", Usage: "Filter listed current paths by explicitness."}, false, func(input **configCommandInput[I, S], value commandkit.Supplied[bool]) { (*input).explicit = value }),
		)
	}
	if operation == Show {
		flags = append(flags, commandkit.ValueFlag(commandkit.FlagMeta{Name: "path", Usage: "JSON Pointer to one effective value."}, (*string)(nil), parseConfigString, func(input **configCommandInput[I, S], value commandkit.Supplied[string]) { (*input).path = value }))
	}
	if operation == Sources {
		flags = append(flags, commandkit.ValueFlag(commandkit.FlagMeta{Name: "source-id", Usage: "Select one source ID from this acquisition."}, (*string)(nil), parseConfigString, func(input **configCommandInput[I, S], value commandkit.Supplied[string]) { (*input).sourceID = value }))
	}
	flags = append(flags, commandkit.CaptureFlags(prepared.bindingsByOperation[operation], func(input **configCommandInput[I, S]) *commandkit.FlagValues[I] {
		if input == nil || *input == nil {
			return nil
		}
		return &(*input).values
	})...)
	if operation == Diff {
		flags = append(flags, commandkit.CaptureFlags(prepared.againstBindings, func(input **configCommandInput[I, S]) *commandkit.FlagValues[I] {
			if input == nil || *input == nil {
				return nil
			}
			return &(*input).againstValues
		})...)
	}

	name, summary := operationDeclaration(operation)
	return commandkit.NewCommand(commandkit.CommandSpec[*configCommandInput[I, S]]{
		Name: name, Summary: summary,
		Description: operationDescription(operation),
		NewInput:    func() *configCommandInput[I, S] { return &configCommandInput[I, S]{} },
		Flags:       flags,
		CheckInput: func(input *configCommandInput[I, S]) error {
			if input == nil {
				return fmt.Errorf("configuration input must not be nil")
			}
			return prepareConfigOperation(prepared, operation, input)
		},
		Run: func(invocation commandkit.Invocation, input *configCommandInput[I, S]) commandkit.Outcome {
			return runConfigOperation(invocation, operation, input)
		},
	})
}

func operationDescription(operation Operation) string {
	if operation == Explain {
		return "Use --list to discover paths or --path POINTER to explain one path."
	}
	return ""
}

func operationDeclaration(operation Operation) (string, string) {
	switch operation {
	case Validate:
		return "validate", "Validate configuration."
	case Show:
		return "show", "Show effective configuration."
	case Sources:
		return "sources", "List configuration sources."
	case Explain:
		return "explain", "Explain a configuration path."
	case Diff:
		return "diff", "Compare two configuration selections."
	default:
		return string(operation), "Inspect configuration."
	}
}

func prepareConfigOperation[I, S any](prepared *preparedSuite[I, S], operation Operation, input *configCommandInput[I, S]) error {
	if operation == Validate && !input.details.Value && (len(input.severities) > 0 || len(input.codes) > 0) {
		return fmt.Errorf("--severity and --code require --details")
	}
	if operation == Explain {
		if input.list.Value && input.path.Set {
			return fmt.Errorf("--list and --path cannot be combined")
		}
		if !input.list.Value && (input.historical.Set || input.under.Set || input.explicit.Set) {
			return fmt.Errorf("--historical, --under, and --explicit require --list")
		}
		if !input.list.Value && !input.path.Set {
			input.plan = &configOperationPlan[I, S]{prepared: prepared, operation: operation, help: true}
			return nil
		}
	}

	scopeName := "app"
	if input.scope.Set {
		scopeName = input.scope.Value
	}
	if scopeName == "" {
		return fmt.Errorf("configuration scope must not be empty")
	}
	if scopeName == "all" && operation != Validate && operation != Show {
		return fmt.Errorf("scope all is supported only for validate and show")
	}
	if scopeName == "all" && operation == Show && input.path.Set {
		return fmt.Errorf("path-selected show requires one scope")
	}

	var selected []*preparedScope[I, S]
	if scopeName == "all" {
		selected = prepared.scopes
	} else if scope, exists := prepared.byName[scopeName]; exists {
		selected = []*preparedScope[I, S]{scope}
	} else {
		return fmt.Errorf("unknown configuration scope %q (available: %s)", scopeName, prepared.scopeChoices)
	}

	for _, scope := range selected {
		if !containsOperation(scope.scope.Operations, operation) {
			return fmt.Errorf("configuration scope %q does not support %s (available: %s)", scope.scope.Name, operation, joinOperations(scope.scope.Operations))
		}
		if (len(input.selection.Overrides) > 0 || len(input.against.Overrides) > 0) && !scope.scope.Features.Overrides {
			return fmt.Errorf("configuration scope %q does not support overrides", scope.scope.Name)
		}
		if operation == Explain && input.list.Value && !scope.scope.Features.PathDiscovery {
			return fmt.Errorf("configuration scope %q does not support path discovery", scope.scope.Name)
		}
		if operation == Show && input.path.Set && !scope.scope.Features.PathShow {
			return fmt.Errorf("configuration scope %q does not support path-selected show", scope.scope.Name)
		}
	}

	var path configkit.Path
	if (operation == Explain || operation == Show) && input.path.Set {
		parsed, err := configkit.ParsePath(input.path.Value)
		if err != nil {
			return fmt.Errorf("invalid configuration path: %w", err)
		}
		path = parsed
	}
	var under *configkit.Path
	if input.under.Set {
		parsed, err := configkit.ParsePath(input.under.Value)
		if err != nil {
			return fmt.Errorf("invalid subtree path: %w", err)
		}
		under = &parsed
	}

	plan := &configOperationPlan[I, S]{
		prepared:   prepared,
		operation:  operation,
		scopeName:  scopeName,
		path:       path,
		pathSet:    input.path.Set,
		sourceID:   input.sourceID,
		details:    input.details.Value,
		check:      input.check.Value,
		severities: append([]configkit.Severity(nil), input.severities...),
		codes:      append([]string(nil), input.codes...),
		list:       input.list.Value,
		historical: input.historical.Value,
		under:      under,
		explicit:   input.explicit,
		scopes:     make([]selectedScopeInput[I, S], 0, len(selected)),
	}
	if operation == Diff {
		scope := selected[0]
		input.selection = cloneSelection(input.selection)
		input.against = cloneSelection(input.against)
		left, err := prepareScopeInput(prepared, input.values, scope, scope.bindings, input.selection, true)
		if err != nil {
			return fmt.Errorf("configuration scope %q left input: %w", scope.scope.Name, err)
		}
		right, err := prepareScopeInput(prepared, input.againstValues, scope, scope.againstBindings, input.against, true)
		if err != nil {
			return fmt.Errorf("configuration scope %q right input: %w", scope.scope.Name, err)
		}
		plan.comparison = &preparedComparison[I, S]{
			scope: scope,
			request: ComparisonRequest[I]{
				Left:  ComparisonSide[I]{Selection: input.selection, Input: left},
				Right: ComparisonSide[I]{Selection: input.against, Input: right},
			},
		}
		input.plan = plan
		return nil
	}
	for _, scope := range selected {
		selection := cloneSelection(input.selection)
		value, err := prepareScopeInput(prepared, input.values, scope, scope.bindings, selection, false)
		if err != nil {
			return fmt.Errorf("configuration scope %q: %w", scope.scope.Name, err)
		}
		plan.scopes = append(plan.scopes, selectedScopeInput[I, S]{scope: scope, input: value, selection: selection})
	}
	input.plan = plan
	return nil
}

func prepareScopeInput[I, S any](prepared *preparedSuite[I, S], values commandkit.FlagValues[I], scope *preparedScope[I, S], bindings []commandkit.Flag[I], selection Selection, suppliedOnly bool) (I, error) {
	var value I
	if prepared.newInput != nil {
		value = prepared.newInput()
	}
	// Availability was checked before this helper, so every binding for the
	// selected scope belongs to the operation's captured union.
	apply := values.ApplyTo
	if suppliedOnly {
		apply = values.ApplySuppliedTo
	}
	if err := apply(&value, bindings...); err != nil {
		return value, err
	}
	if prepared.checkInput != nil {
		if err := prepared.checkInput(scope.scope.Name, selection, value); err != nil {
			return value, err
		}
	}
	return value, nil
}

func joinOperations(operations []Operation) string {
	values := make([]string, len(operations))
	for index, operation := range operations {
		values[index] = string(operation)
	}
	if len(values) == 0 {
		return "none"
	}
	return strings.Join(values, ", ")
}