package cli

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"

	configkit "gitea.maximumdirect.net/eric/ConfigKit"
	appconfig "gitea.maximumdirect.net/eric/scriptorium/internal/config"
)

type configurationSource struct {
	ID    string          `json:"id"`
	Label string          `json:"label"`
	Layer configkit.Layer `json:"layer"`
	Path  string          `json:"path,omitempty"`
}

func configCommand(args []string, stdout, stderr io.Writer) int {
	if len(args) == 0 {
		fmt.Fprintln(stderr, "config parse error: configuration mode is required")
		return ExitRuntimeError
	}
	mode := args[0]
	if mode != "validate" && mode != "show" && mode != "sources" && mode != "explain" {
		fmt.Fprintln(stderr, "config parse error: unknown configuration mode")
		return ExitRuntimeError
	}

	fs := flag.NewFlagSet("config "+mode, flag.ContinueOnError)
	fs.SetOutput(io.Discard)
	var path, overlay, pointer string
	registerConfigSelectionFlags(fs, &path, &overlay)
	registerConfigurationOverrides(fs)
	if mode == "explain" {
		fs.StringVar(&pointer, "path", "", "configuration path as a JSON Pointer")
	}
	if err := fs.Parse(args[1:]); err != nil {
		writeApplicationError(stderr, "config parse", err)
		return ExitRuntimeError
	}
	if fs.NArg() != 0 {
		fmt.Fprintln(stderr, "config parse error: positional arguments are not accepted")
		return ExitRuntimeError
	}
	var explanationPath configkit.Path
	if mode == "explain" {
		if !flagWasSet(fs, "path") {
			fmt.Fprintln(stderr, "config parse error: --path is required")
			return ExitRuntimeError
		}
		var err error
		explanationPath, err = configkit.ParsePath(pointer)
		if err != nil {
			fmt.Fprintln(stderr, "config parse error: --path must be a JSON Pointer")
			return ExitRuntimeError
		}
	}

	result, err := appconfig.Load(appconfig.LoadOptions{
		Path: path, Explicit: flagWasSet(fs, "config"), Overlay: overlay,
		Overrides: applicationOverrides(fs),
	})
	if err != nil {
		writeApplicationError(stderr, "config", err)
		return ExitRuntimeError
	}
	if err := writeApplicationWarnings(stderr, result.Diagnostics()); err != nil {
		return ExitRuntimeError
	}
	switch mode {
	case "validate":
		return ExitOK
	case "show":
		err = result.WriteEffective(stdout)
	case "sources":
		sources := make([]configurationSource, 0, len(result.Sources()))
		for _, source := range result.Sources() {
			sources = append(sources, configurationSource{
				ID: source.ID, Label: source.Label, Layer: source.Layer, Path: source.Path,
			})
		}
		err = json.NewEncoder(stdout).Encode(sources)
	case "explain":
		err = result.WriteExplanation(stdout, explanationPath)
	}
	if err != nil {
		fmt.Fprintf(stderr, "config output error: %v\n", err)
		return ExitRuntimeError
	}
	return ExitOK
}

func registerConfigurationOverrides(fs *flag.FlagSet) {
	fs.String("prompt-dir", "", "prompt-definition directory override")
	fs.String("profile-dir", "", "profile directory override")
	fs.String("schema-dir", "", "schema directory override")
	fs.String("addr", "", "HTTP listen address override")
	fs.String("artifact-root", "", "HTTP artifact root override")
	fs.Int64("max-request-bytes", 0, "HTTP request byte limit override")
	fs.Int64("max-artifact-bytes", 0, "HTTP artifact byte limit override")
	fs.Int64("max-response-bytes", 0, "HTTP response byte limit override")
}