package theme

import (
	"embed"
	"encoding/json"
	"fmt"
	"io/fs"
	"path/filepath"
	"sort"
	"strings"

	"github.com/charmbracelet/lipgloss"
)

//go:embed themes/*.json
var embeddedThemes embed.FS

// LoadEmbeddedThemesJSON reads all embedded theme JSON files and unmarshals
// them into ThemeJSON objects keyed by theme name.
func LoadEmbeddedThemesJSON() (map[string]ThemeJSON, error) {
	paths, err := fs.Glob(embeddedThemes, "themes/*.json")
	if err != nil {
		return nil, err
	}
	sort.Strings(paths)

	out := make(map[string]ThemeJSON, len(paths))
	for _, path := range paths {
		b, readErr := embeddedThemes.ReadFile(path)
		if readErr != nil {
			return nil, fmt.Errorf("read embedded theme %q: %w", path, readErr)
		}

		var th ThemeJSON
		if unmarshalErr := json.Unmarshal(b, &th); unmarshalErr != nil {
			return nil, fmt.Errorf("decode embedded theme %q: %w", path, unmarshalErr)
		}

		if strings.TrimSpace(th.Name) == "" {
			th.Name = strings.TrimSuffix(filepath.Base(path), ".json")
		}

		out[th.Name] = th
	}

	return out, nil
}

func MapEmbeddedThemeToEditorTheme(em map[string]ThemeJSON) map[string]EditorTheme {
	out := make(map[string]EditorTheme, len(em))

	for name, in := range em {
		line := styleFromJSON(in.Line)
		lineBg := colorString(in.Line.BG)

		syntaxExact := make(map[string]lipgloss.Style, len(in.Syntax.Exact))
		for capture, col := range in.Syntax.Exact {
			c := normalizeCaptureKey(capture)
			if c == "" {
				continue
			}
			syntaxExact[c] = syntaxColorStyle(col, lineBg)
		}

		syntaxGroup := make(map[string]lipgloss.Style, len(in.Syntax.Group))
		for group, col := range in.Syntax.Group {
			g := normalizeCaptureKey(group)
			if g == "" {
				continue
			}
			syntaxGroup[g] = syntaxColorStyle(col, lineBg)
		}

		key := strings.TrimSpace(name)
		if key == "" {
			key = strings.TrimSpace(in.Name)
		}
		if key == "" {
			continue
		}

		out[key] = EditorTheme{
			Cursors: CursorTheme{
				Normal:  styleFromJSON(in.Cursors.Normal),
				Insert:  styleFromJSON(in.Cursors.Insert),
				Command: styleFromJSON(in.Cursors.Command),
				Replace: styleFromJSON(in.Cursors.Replace),
			},
			Gutter: GutterTheme{
				Default:     styleFromJSON(in.Gutter.Default),
				CurrentLine: styleFromJSON(in.Gutter.CurrentLine),
			},
			VisualHightlight: styleFromJSON(in.VisualHighlight),
			StatusBar: StatusBarTheme{
				Default: styleFromJSON(in.StatusBar.Default),
			},
			CommandLine: CommandLineTheme{
				Error:           styleFromJSON(in.CommandLine.Error),
				OutputBorder:    styleFromJSON(in.CommandLine.OutputBorder),
				ContinueMessage: styleFromJSON(in.CommandLine.ContinueMessage),
			},
			Line:       line,
			Background: styleFromJSON(in.Background),
			Syntax: SyntaxTheme{
				Exact: syntaxExact,
				Group: syntaxGroup,
			},
		}
	}

	return out
}

func styleFromJSON(in ColorStyleJSON) lipgloss.Style {
	out := lipgloss.NewStyle()

	if fg := colorString(in.FG); fg != "" {
		out = out.Foreground(lipgloss.Color(fg))
	}
	if bg := colorString(in.BG); bg != "" {
		out = out.Background(lipgloss.Color(bg))
	}

	return out
}

func colorString(c string) string {
	return strings.TrimSpace(c)
}

func normalizeCaptureKey(k string) string {
	k = strings.TrimSpace(strings.ToLower(k))
	k = strings.TrimPrefix(k, "@")
	return k
}

func syntaxColorStyle(fg, bg string) lipgloss.Style {
	out := lipgloss.NewStyle()

	if f := colorString(fg); f != "" {
		out = out.Foreground(lipgloss.Color(f))
	}
	if b := colorString(bg); b != "" {
		out = out.Background(lipgloss.Color(b))
	}

	return out
}