package ckconfig

import (
	"bytes"
	"fmt"
	"io"
	"strconv"

	commandkit "go.maximumdirect.net/commandkit"
	configkit "go.maximumdirect.net/configkit"
	"go.yaml.in/yaml/v4"
)

type sourceReport struct {
	Scope   string      `yaml:"scope"`
	Sources []sourceDTO `yaml:"sources"`
}

type sourceDTO struct {
	ID                    string                    `yaml:"id"`
	Label                 string                    `yaml:"label"`
	Path                  string                    `yaml:"path"`
	Destination           string                    `yaml:"destination"`
	Placement             string                    `yaml:"placement"`
	DestinationIsFallback bool                      `yaml:"destination_is_fallback"`
	Layer                 string                    `yaml:"layer"`
	Kind                  string                    `yaml:"kind"`
	UnderlayIndex         int                       `yaml:"underlay_index"`
	ImportedFrom          *locationDTO              `yaml:"imported_from"`
	VersionEvidence       *sourceVersionEvidenceDTO `yaml:"version_evidence"`
	EmptyImportSelections []emptyImportSelectionDTO `yaml:"empty_import_selections"`
}

type emptyImportSelectionDTO struct {
	Path     string      `yaml:"path"`
	Location locationDTO `yaml:"location"`
	Selector string      `yaml:"selector"`
}

type locationDTO struct {
	SourceID string `yaml:"source_id"`
	Line     int    `yaml:"line"`
	Column   int    `yaml:"column"`
}

type sourceVersionEvidenceDTO struct {
	Path     string       `yaml:"path"`
	Version  versionDTO   `yaml:"version"`
	Location *locationDTO `yaml:"location"`
	Redacted bool         `yaml:"redacted"`
}

type versionDTO struct {
	Present bool   `yaml:"present"`
	Null    bool   `yaml:"null"`
	Text    string `yaml:"text"`
}

func runConfigSources[I, S any](invocation commandkit.Invocation, plan *configOperationPlan[I, S], state S) commandkit.Outcome {
	selected := plan.scopes[0]
	name := selected.scope.scope.Name
	reporter := invocation.Reporter()
	if err := invocation.Context.Err(); err != nil {
		return configFailure("Configuration source listing was canceled.", commandkit.Explanation{}, err)
	}
	if selected.scope.scope.Acquire == nil {
		cause := fmt.Errorf("configuration scope %q has no acquisition callback", name)
		return configFailure(fmt.Sprintf("Unable to list sources for configuration scope %q.", name), commandkit.Explanation{}, cause)
	}
	acquired, acquireErr := selected.scope.scope.Acquire(invocation.Context, Request{
		Operation: Sources,
		Selection: plan.selection,
	}, selected.input, state)
	queueConfigDiagnostics(reporter, acquired.Diagnostics)
	if acquireErr != nil {
		return configFailure(fmt.Sprintf("Unable to list sources for configuration scope %q.", name), acquired.Explanation, acquireErr)
	}
	if err := invocation.Context.Err(); err != nil {
		return configFailure("Configuration source listing was canceled.", acquired.Explanation, err)
	}
	if acquired.Value.Sources == nil {
		cause := fmt.Errorf("configuration scope %q did not provide a source reader", name)
		return configFailure("Configuration scope did not provide source information.", acquired.Explanation, cause)
	}

	sources := acquired.Value.Sources.Sources()
	document := sourceReport{Scope: name, Sources: make([]sourceDTO, 0, len(sources))}
	for _, source := range sources {
		placement := "mapping"
		if source.PlacementMode == configkit.PlacementModeSequenceItem {
			placement = "sequence_item"
		}
		item := sourceDTO{
			ID:                    source.ID,
			Label:                 source.Label,
			Path:                  source.Path,
			Destination:           source.Destination.String(),
			Placement:             placement,
			DestinationIsFallback: source.DestinationIsFallback,
			Layer:                 string(source.Layer),
			Kind:                  string(source.Kind),
			UnderlayIndex:         source.UnderlayIndex,
			EmptyImportSelections: make([]emptyImportSelectionDTO, 0, len(source.EmptyImportSelections)),
		}
		if source.ImportedFrom != nil {
			item.ImportedFrom = &locationDTO{SourceID: source.ImportedFrom.SourceID, Line: source.ImportedFrom.Line, Column: source.ImportedFrom.Column}
		}
		if source.VersionEvidence != nil {
			check := source.VersionEvidence
			item.VersionEvidence = &sourceVersionEvidenceDTO{
				Path: check.Path.String(),
				Version: versionDTO{
					Present: check.Version.Present,
					Null:    check.Version.Null,
					Text:    check.Version.Text,
				},
				Redacted: check.Redacted,
			}
			if check.Location != nil {
				item.VersionEvidence.Location = &locationDTO{SourceID: check.Location.SourceID, Line: check.Location.Line, Column: check.Location.Column}
			}
		}
		for _, selection := range source.EmptyImportSelections {
			item.EmptyImportSelections = append(item.EmptyImportSelections, emptyImportSelectionDTO{Path: selection.Path.String(), Location: locationDTO{SourceID: selection.Location.SourceID, Line: selection.Location.Line, Column: selection.Location.Column}, Selector: string(selection.Selector)})
		}
		document.Sources = append(document.Sources, item)
	}
	if err := invocation.Context.Err(); err != nil {
		return configFailure("Configuration source listing was canceled.", acquired.Explanation, err)
	}
	return renderPreparedConfigReport(invocation, acquired.Explanation, func() ([]byte, error) {
		var report bytes.Buffer
		if plan.format == "yaml" {
			if err := encodeYAML(&report, document); err != nil {
				return nil, err
			}
		} else {
			writeSourceReportText(&report, document)
		}
		return report.Bytes(), nil
	})
}

func writeSourceReportText(writer *bytes.Buffer, document sourceReport) {
	_, _ = fmt.Fprintf(writer, "Scope: %s\n", strconv.Quote(document.Scope))
	if len(document.Sources) == 0 {
		_, _ = writer.WriteString("Sources: []\n")
		return
	}
	_, _ = writer.WriteString("Sources:\n")
	for _, source := range document.Sources {
		_, _ = fmt.Fprintf(writer, "  - id: %s\n", strconv.Quote(source.ID))
		_, _ = fmt.Fprintf(writer, "    label: %s\n", strconv.Quote(source.Label))
		_, _ = fmt.Fprintf(writer, "    path: %s\n", strconv.Quote(source.Path))
		_, _ = fmt.Fprintf(writer, "    destination: %s\n", strconv.Quote(source.Destination))
		_, _ = fmt.Fprintf(writer, "    placement: %s\n", strconv.Quote(source.Placement))
		_, _ = fmt.Fprintf(writer, "    destination_is_fallback: %t\n", source.DestinationIsFallback)
		_, _ = fmt.Fprintf(writer, "    layer: %s\n", strconv.Quote(source.Layer))
		_, _ = fmt.Fprintf(writer, "    kind: %s\n", strconv.Quote(source.Kind))
		_, _ = fmt.Fprintf(writer, "    underlay_index: %d\n", source.UnderlayIndex)
		if source.ImportedFrom == nil {
			_, _ = writer.WriteString("    imported_from: null\n")
		} else {
			_, _ = fmt.Fprintf(writer, "    imported_from: {source_id: %s, line: %d, column: %d}\n",
				strconv.Quote(source.ImportedFrom.SourceID), source.ImportedFrom.Line, source.ImportedFrom.Column)
		}
		if source.VersionEvidence == nil {
			_, _ = writer.WriteString("    version_evidence: null\n")
		} else {
			check := source.VersionEvidence
			_, _ = fmt.Fprintf(writer, "    version_evidence:\n      path: %s\n", strconv.Quote(check.Path))
			_, _ = fmt.Fprintf(writer, "      version:\n        present: %t\n        null: %t\n        text: %s\n",
				check.Version.Present, check.Version.Null, strconv.Quote(check.Version.Text))
			if check.Location == nil {
				_, _ = writer.WriteString("      location: null\n")
			} else {
				_, _ = fmt.Fprintf(writer, "      location: {source_id: %s, line: %d, column: %d}\n",
					strconv.Quote(check.Location.SourceID), check.Location.Line, check.Location.Column)
			}
			_, _ = fmt.Fprintf(writer, "      redacted: %t\n", check.Redacted)
		}
		if len(source.EmptyImportSelections) == 0 {
			_, _ = writer.WriteString("    empty_import_selections: []\n")
		} else {
			_, _ = writer.WriteString("    empty_import_selections:\n")
			for _, selection := range source.EmptyImportSelections {
				_, _ = fmt.Fprintf(writer, "      - path: %s\n        location: {source_id: %s, line: %d, column: %d}\n        selector: %s\n", strconv.Quote(selection.Path), strconv.Quote(selection.Location.SourceID), selection.Location.Line, selection.Location.Column, strconv.Quote(selection.Selector))
			}
		}
	}
}

func encodeYAML(writer io.Writer, document any) error {
	encoder := yaml.NewEncoder(writer)
	encoder.SetIndent(2)
	return encoder.Encode(document)
}

func locationReports(locations []configkit.Location) []locationDTO {
	report := make([]locationDTO, 0, len(locations))
	for _, location := range locations {
		report = append(report, locationDTO{SourceID: location.SourceID, Line: location.Line, Column: location.Column})
	}
	return report
}