package config

import (
	"errors"
	"fmt"
	"maps"
	"os"
	"path/filepath"

	"gopkg.in/yaml.v2"
)

// The properties that are depended upon in the source code are declared explicitly in the config struct.
// The constructors will set default values for most.
// Depending on the command, different defaults will be used (serve is assumed to be a "dev" environment
// while build is assumed to be prod)
// Some defaults could be overridden by cli flags (eg disable live reload on serve).
// The user can override some of those via config yaml.
// The non declared values found in config yaml will just be passed as site.config values

type Config struct {
	RootDir     string
	SrcDir      string
	TargetDir   string
	LayoutsDir  string
	IncludesDir string
	DataDir     string

	SiteUrl        string
	PostFormat     string
	Lang           string
	HighlightTheme string

	Minify        bool
	LiveReload    bool
	LinkStatic    bool
	IncludeDrafts bool

	ServerHost string
	ServerPort int

	pageDefaults map[string]interface{}

	// the user provided overrides, as found in config.yml
	// these will passed as found as template context
	overrides map[string]interface{}
}

func Load(rootDir string) (*Config, error) {
	// TODO allow to disable minify

	config := &Config{
		RootDir:        rootDir,
		SrcDir:         filepath.Join(rootDir, "src"),
		TargetDir:      filepath.Join(rootDir, "target"),
		LayoutsDir:     filepath.Join(rootDir, "layouts"),
		IncludesDir:    filepath.Join(rootDir, "includes"),
		DataDir:        filepath.Join(rootDir, "data"),
		PostFormat:     "blog/:title.org",
		Lang:           "en",
		HighlightTheme: "github",
		Minify:         true,
		LiveReload:     false,
		LinkStatic:     false,
		IncludeDrafts:  false,
		pageDefaults:   map[string]interface{}{},
	}

	// load overrides from config.yml
	configPath := filepath.Join(rootDir, "config.yml")
	yamlContent, err := os.ReadFile(configPath)

	if errors.Is(err, os.ErrNotExist) {
		// config file is not mandatory
		return config, nil
	} else if err != nil {
		return nil, err
	}

	err = yaml.Unmarshal(yamlContent, &config.overrides)
	if err != nil {
		return nil, err
	}

	// set user-provided overrides of declared config keys
	// TODO less copypasty way of declaring config overrides
	if url, found := config.overrides["url"]; found {
		config.SiteUrl = url.(string)
	}
	if format, found := config.overrides["post_format"]; found {
		config.PostFormat = format.(string)
	}
	if format, found := config.overrides["lang"]; found {
		config.Lang = format.(string)
	}
	if format, found := config.overrides["highlight_theme"]; found {
		config.HighlightTheme = format.(string)
	}

	return config, nil
}

func LoadDev(rootDir string, host string, port int, reload bool) (*Config, error) {
	// TODO revisit is this Load vs LoadDevServer is the best way to handle both modes
	// TODO some of the options need to be overridable: host, port, live reload at least

	config, err := Load(rootDir)
	if err != nil {
		return nil, err
	}

	// setup serve command specific overrides (these could be eventually tweaked with flags)
	config.ServerHost = host
	config.ServerPort = port
	config.LiveReload = reload
	config.Minify = false
	config.LinkStatic = true
	config.IncludeDrafts = true
	config.SiteUrl = fmt.Sprintf("http://%s:%d", config.ServerHost, config.ServerPort)

	return config, nil
}

func (config Config) AsContext() map[string]interface{} {
	context := map[string]interface{}{
		"url": config.SiteUrl,
	}
	maps.Copy(context, config.overrides)
	return context
}