package main

import (
	"bytes"
	"embed"
	"fmt"
	"html/template"
	"io"
	"io/fs"
	"log/slog"
	"os"
	"path/filepath"
	"strings"

	"github.com/alecthomas/kong"
	"github.com/aquilax/cooklang-go"
)

const (
	stepPrefix       = "<p>"
	stepSuffix       = "</p>"
	ingredientPrefix = "<span class=\"ingredient\">"
	ingredientSuffix = "</span>"
	cookwarePrefix   = "<span class=\"cookware\">"
	cookwareSuffix   = "</span>"
	timerPrefix      = "<span class=\"timer\">"
	timerSuffix      = "</span>"
)

//go:embed templates
var embedTmpl embed.FS
var imageExtensions = []string{".jpg", ".jpeg", ".png"}
var funcMap = template.FuncMap{
	"recipeImage": recipeImage,
	"recipeSteps": func(r cooklang.Recipe, path string) template.HTML {
		var str = ""
		for i, step := range r.Steps {
			d := step.Directions

			ingredients := make([]string, len(step.Ingredients))
			for i, ingredient := range step.Ingredients {
				ingredients[i] = ingredient.Name
			}
			d = hydrate(d, ingredients, ingredientPrefix, ingredientSuffix)

			cookwareEls := make([]string, len(step.Cookware))
			for i, cookware := range step.Cookware {
				cookwareEls[i] = cookware.Name
			}
			d = hydrate(d, cookwareEls, cookwarePrefix, cookwareSuffix)

			timers := make([]string, len(step.Timers))
			for i, timer := range step.Timers {
				timers[i] = fmt.Sprintf("%v %s", timer.Duration, timer.Unit)
			}
			d = hydrate(d, timers, timerPrefix, timerSuffix)

			recipeImagePath := recipeImageForStep(path, i)
			if recipeImagePath != "" {
				str += fmt.Sprintf("<img class=\"stepimage stepimage-%d\" src=\"%s\" />", i, recipeImagePath)
			}
			str += stepPrefix + d + stepSuffix
		}

		return template.HTML(str)
	},
}

func recipeImageForStep(recipepath string, step int) string {
	ext := filepath.Ext(recipepath)
	imagepath := fmt.Sprintf("%s.%d%s", strings.TrimSuffix(recipepath, ext), step, ext)
	return recipeImage(imagepath)
}

func recipeImage(recipepath string) string {
	pathWithoutExt := strings.TrimSuffix(recipepath, filepath.Ext(recipepath))
	for _, ext := range imageExtensions {
		imagepath := fmt.Sprintf("%s%s", pathWithoutExt, ext)
		if fi, err := os.Stat(imagepath); err == nil && !fi.IsDir() {
			return filepath.Base(imagepath)
		}
	}
	return ""
}

func hydrate(text string, elements []string, prefix, suffix string) string {
	cursor := 0
	for _, el := range elements {
		slog.Debug("Chasing element", "cursor", cursor, "element", el)
		idx := strings.Index(text[cursor:], el)
		first := text[:cursor+idx]
		rest := text[cursor+idx+len(el):]
		text = first + prefix + el + suffix + rest
		cursor += idx + len(prefix+el+suffix)
		slog.Debug("Parsed element", "newCursor", cursor, "first", first, "rest", rest)
	}
	return text
}

func executeTemplate(name string, data any) ([]byte, error) {
	path := filepath.Join("templates", fmt.Sprintf("%s.html.tmpl", name))
	b, err := embedTmpl.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("cannot read embedded file %q: %w", path, err)
	}

	tmpl, err := template.New("").Funcs(funcMap).Parse(string(b))
	if err != nil {
		return nil, fmt.Errorf("cannot parse template %q: %w", path, err)
	}

	var strb bytes.Buffer
	if err := tmpl.Execute(&strb, data); err != nil {
		return nil, fmt.Errorf("cannot execute template %q: %w", path, err)
	}

	return strb.Bytes(), nil
}

func executeTemplateToFile(tmplName string, data any, filename string) error {
	contents, err := executeTemplate(tmplName, data)
	if err != nil {
		return fmt.Errorf("cannot execute %q template: %w", tmplName, err)
	}

	if err := os.WriteFile(filename, contents, 0755); err != nil {
		return fmt.Errorf("cannot write %q contents to %q: %w", tmplName, filename, err)
	}

	return nil
}

func getRelpath(name string) string {
	return strings.Repeat("../", strings.Count(name, "/"))
}

func copyFile(srcpath, dstpath string) error {
	src, err := os.Open(srcpath)
	if err != nil {
		return fmt.Errorf("cannot open src file %q: %w", srcpath, err)
	}
	defer src.Close()

	return copyToFile(src, dstpath)
}

func copyToFile(src io.Reader, dstpath string) error {
	dst, err := os.Create(dstpath)
	if err != nil {
		return fmt.Errorf("cannot open dst file %q: %w", dstpath, err)
	}
	defer dst.Close()

	if _, err := io.Copy(dst, src); err != nil {
		return fmt.Errorf("cannot copy to file %q: %w", dstpath, err)
	}

	return dst.Sync()
}

func main() {
	ctx := kong.Parse(&cli)
	if cli.Debug {
		slog.SetLogLoggerLevel(slog.LevelDebug)
	}

	if err := ctx.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "error: %s\n", err)
		os.Exit(1)
	}
}

func isExcluded(name string) bool {
	return strings.HasPrefix(strings.ToUpper(name), "README")
}

func (g *generateCmd) Run() error {
	fi, err := os.Stat(g.Output)
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("cannot stat %q: %w", g.Output, err)
	}

	if !os.IsNotExist(err) && !fi.IsDir() {
		return fmt.Errorf("path %q is not a directory", g.Output)
	} else {
		if err := os.RemoveAll(g.Output); err != nil {
			return fmt.Errorf("cannot remove %q: %w", g.Output, err)
		}
	}
	if err := os.Mkdir(g.Output, 0755); err != nil {
		return fmt.Errorf("cannot create directory on path %q: %w", g.Output, err)
	}

	walkErr := filepath.WalkDir(g.Path, func(path string, d fs.DirEntry, err error) error {
		slog.Debug("Walking through file", "path", path)

		if isExcluded(d.Name()) {
			slog.Debug("Excluded file, skipping", "name", d.Name())
			return nil
		}

		apath, err := filepath.Abs(path)
		if err != nil {
			return fmt.Errorf("cannot get the abs path for %q: %w", path, err)
		}

		relpath, err := filepath.Rel(g.Path, apath)
		if err != nil {
			return fmt.Errorf("cannot get relative path for %s: %w", apath, err)
		}

		ext := filepath.Ext(d.Name())
		if d.IsDir() {
			dirpath := filepath.Join(g.Output, relpath)
			slog.Debug("Directory found, creating output dir", "path", path, "dirpath", dirpath)
			if err := os.MkdirAll(dirpath, 0755); err != nil {
				return fmt.Errorf("cannot create directory %s: %w", dirpath, err)
			}
			return nil
		}

		if ext != ".cook" {
			dstPath := filepath.Join(g.Output, relpath)
			slog.Debug("Non-recipe file found, copying", "src", path, "dst", dstPath)
			if err := copyFile(path, dstPath); err != nil {
				return fmt.Errorf("cannot copy file from %q to %q: %w", path, dstPath, err)
			}
			slog.Debug("File copy successful", "src", path, "dst", dstPath)
			return nil
		}

		slog.Debug("Parsing file", "name", path)
		recipe, err := cooklang.ParseFile(path)
		if err != nil {
			return fmt.Errorf("cannot parse file %q: %w", path, err)
		}

		if len(recipe.Steps) == 0 {
			slog.Debug("File is not a recipe", "name", path)
			return nil
		}

		slog.Debug("Parsed file", "path", path, "steps", len(recipe.Steps))

		filenameWithoutExt := strings.TrimSuffix(d.Name(), ext)
		recipeName := filenameWithoutExt
		if name, ok := recipe.Metadata[g.NameKey]; ok {
			recipeName = name
		}

		recipeDistPath := filepath.Join(g.Output, filepath.Dir(relpath), fmt.Sprintf("%s.html", filenameWithoutExt))
		data := map[string]any{"name": recipeName, "recipe": recipe, "path": path, "relpath": getRelpath(relpath)}
		slog.Debug("Executing template", "recipeName", recipeName, "recipeWebPath", recipeDistPath)
		if err := executeTemplateToFile("recipe", data, recipeDistPath); err != nil {
			return fmt.Errorf("cannot execute template \"recipe\" to file %q: %w", recipeDistPath, err)
		}

		return nil
	})
	if walkErr != nil {
		return fmt.Errorf("error while walking directory %q: %w", g.Path, walkErr)
	}

	styleFile, err := embedTmpl.Open(filepath.Join("templates", "style.css"))
	if err != nil {
		return fmt.Errorf("cannot read style.css embed file: %w", err)
	}

	if err := copyToFile(styleFile, filepath.Join(g.Output, "style.css")); err != nil {
		return fmt.Errorf("cannot copy style.css: %w", err)
	}

	return nil
}