package commandkit

import (
	"bytes"
	"fmt"
	"strconv"
)

func newConfigSourcesCommand[C any](prepared *preparedConfigSuite[C]) (Command, error) {
	spec := CommandSpec[configInput[C]]{
		Name:    string(ConfigSources),
		Summary: "List configuration sources used by a scope.",
		Flags:   configInputFlags(prepared.suite, "text"),
		CheckInput: func(input configInput[C]) error {
			_, err := preflightConfig(prepared, input, ConfigSources)
			return err
		},
		Run: func(invocation Invocation, input configInput[C]) Outcome {
			return runConfigSources(invocation, prepared, input)
		},
	}
	return NewCommand(spec)
}

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"`
	Layer         string       `yaml:"layer"`
	Kind          string       `yaml:"kind"`
	UnderlayIndex int          `yaml:"underlay_index"`
	ImportedFrom  *locationDTO `yaml:"imported_from"`
}

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

func runConfigSources[C any](invocation Invocation, prepared *preparedConfigSuite[C], input configInput[C]) Outcome {
	if err := invocation.Context.Err(); err != nil {
		return Failure(err)
	}
	scopeNames, err := selectConfigScopes(prepared, input, ConfigSources)
	if err != nil {
		return Failure(err)
	}
	contexts := contextsForScopes(prepared, input, scopeNames)
	name := scopeNames[0]
	scope, ok := findConfigScope(prepared, name)
	if !ok || scope.Acquire == nil {
		return sourceReportFailure(fmt.Errorf("configuration scope %q has no acquisition callback", name), nil, false)
	}
	if err := invocation.Context.Err(); err != nil {
		return sourceReportFailure(err, nil, false)
	}
	acquired, acquireErr := scope.Acquire(invocation.Context, ConfigRequest{Operation: ConfigSources, Selection: input.Selection}, contexts[name])
	diagnostics := append([]Diagnostic(nil), acquired.Diagnostics...)
	if acquireErr != nil {
		return sourceReportFailure(acquireErr, diagnostics, false)
	}
	if err := invocation.Context.Err(); err != nil {
		return sourceReportFailure(err, diagnostics, false)
	}

	if acquired.Value.Sources == nil {
		return sourceReportFailure(fmt.Errorf("configuration scope %q did not provide a source reader", name), diagnostics, false)
	}
	sources := acquired.Value.Sources.Sources()
	document := sourceReport{Scope: name, Sources: make([]sourceDTO, 0, len(sources))}
	for _, source := range sources {
		item := sourceDTO{
			ID:            source.ID,
			Label:         source.Label,
			Path:          source.Path,
			Layer:         string(source.Layer),
			Kind:          string(source.Kind),
			UnderlayIndex: source.UnderlayIndex,
		}
		if source.ImportedFrom != nil {
			item.ImportedFrom = &locationDTO{SourceID: source.ImportedFrom.SourceID, Line: source.ImportedFrom.Line, Column: source.ImportedFrom.Column}
		}
		document.Sources = append(document.Sources, item)
	}

	var report bytes.Buffer
	if input.Format == "yaml" {
		if err := encodeYAML(&report, document); err != nil {
			return sourceReportFailure(err, diagnostics, false)
		}
	} else {
		writeSourceReportText(&report, document)
	}
	if err := invocation.Context.Err(); err != nil {
		return sourceReportFailure(err, diagnostics, false)
	}
	if err := writeReport(invocation.Streams.Out, report.Bytes()); err != nil {
		outcome := sourceReportFailure(err, diagnostics, true)
		outcome.DeliveryError = err
		return outcome
	}
	outcome := Success()
	outcome.Diagnostics = diagnostics
	return outcome
}

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, "    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)
		}
	}
}

func sourceReportFailure(cause error, diagnostics []Diagnostic, reportStarted bool) Outcome {
	outcome := Failure(cause)
	outcome.Diagnostics = diagnostics
	outcome.ReportIncomplete = reportStarted
	return outcome
}