// getVars returns list of variables defined in a text file and actual file
// content following the variables declaration. Header is separated from
// content by an empty line. Header is in YAML
// If no empty newline is found - file is treated as content-only.
package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"gopkg.in/yaml.v3"
)

func getVars(path string, globals Vars) (Vars, string, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, "", err
	}
	s := string(b)

	// Pick some default values for content-dependent variables
	v := Vars{}
	title := strings.Replace(strings.Replace(path, "_", " ", -1), "-", " ", -1)
	v["title"] = strings.ToTitle(title)
	v["description"] = ""
	v["file"] = path
	v["url"] = path[:len(path)-len(filepath.Ext(path))] + ".html"
	v["output"] = filepath.Join(PUBDIR, v["url"])

	// Override default values with globals
	for name, value := range globals {
		v[name] = value
	}
	// Add a layout if none is specified
	// For this to work, the layout must be available
	// in AYADIR
	if _, ok := v["layout"]; !ok {
		v["layout"] = "layout.html"
	}
	
	delim := "\n---\n"
	if sep := strings.Index(s, delim); sep == -1 {
		return v, s, nil
	} else {
		header := s[:sep]
		body := s[sep+len(delim):]

		vars := Vars{}
		if err := yaml.Unmarshal([]byte(header), &vars); err != nil {
			fmt.Println("ERROR: Failed to parse header", err)
			return nil, "", err
		} else {
			// Override default values and globals with the ones defined in the file
			for key, value := range vars {
				v[key] = value
			}
		}
		if strings.HasPrefix(v["url"], "./") {
			v["url"] = v["url"][2:]
		}
		return v, body, nil
	}
}