package bundle

import (
    "errors"
    "github.com/eknkc/amber"
    "github.com/spf13/hugo/helpers"
    "html"
    "html/template"
    "io"
    "io/ioutil"
    "os"
    "path/filepath"
    "reflect"
    "strconv"
    "strings"
)

func Gt(a interface{}, b interface{}) bool {
    var left, right int64
    av := reflect.ValueOf(a)

    switch av.Kind() {
    case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
        left = int64(av.Len())
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        left = av.Int()
    case reflect.String:
        left, _ = strconv.ParseInt(av.String(), 10, 64)
    }

    bv := reflect.ValueOf(b)

    switch bv.Kind() {
    case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice:
        right = int64(bv.Len())
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        right = bv.Int()
    case reflect.String:
        right, _ = strconv.ParseInt(bv.String(), 10, 64)
    }

    return left > right
}

// First is exposed to templates, to iterate over the first N items in a
// rangeable list.
func First(limit int, seq interface{}) (interface{}, error) {
    if limit < 1 {
        return nil, errors.New("can't return negative/empty count of items from sequence")
    }

    seqv := reflect.ValueOf(seq)
    // this is better than my first pass; ripped from text/template/exec.go indirect():
    for ; seqv.Kind() == reflect.Ptr || seqv.Kind() == reflect.Interface; seqv = seqv.Elem() {
        if seqv.IsNil() {
            return nil, errors.New("can't iterate over a nil value")
        }
        if seqv.Kind() == reflect.Interface && seqv.NumMethod() > 0 {
            break
        }
    }

    switch seqv.Kind() {
    case reflect.Array, reflect.Slice, reflect.String:
        // okay
    default:
        return nil, errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
    }
    if limit > seqv.Len() {
        limit = seqv.Len()
    }
    return seqv.Slice(0, limit).Interface(), nil
}

func IsSet(a interface{}, key interface{}) bool {
    av := reflect.ValueOf(a)
    kv := reflect.ValueOf(key)

    switch av.Kind() {
    case reflect.Array, reflect.Chan, reflect.Slice:
        if int64(av.Len()) > kv.Int() {
            return true
        }
    case reflect.Map:
        if kv.Type() == av.Type().Key() {
            return av.MapIndex(kv).IsValid()
        }
    }

    return false
}

func ReturnWhenSet(a interface{}, index int) interface{} {
    av := reflect.ValueOf(a)

    switch av.Kind() {
    case reflect.Array, reflect.Slice:
        if av.Len() > index {

            avv := av.Index(index)
            switch avv.Kind() {
            case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
                return avv.Int()
            case reflect.String:
                return avv.String()
            }
        }
    }

    return ""
}

func Highlight(in interface{}, lang string) template.HTML {
    var str string
    av := reflect.ValueOf(in)
    switch av.Kind() {
    case reflect.String:
        str = av.String()
    }

    if strings.HasPrefix(strings.TrimSpace(str), "<pre><code>") {
        str = str[strings.Index(str, "<pre><code>")+11:]
    }
    if strings.HasSuffix(strings.TrimSpace(str), "</code></pre>") {
        str = str[:strings.LastIndex(str, "</code></pre>")]
    }
    return template.HTML(helpers.Highlight(html.UnescapeString(str), lang))
}

func SafeHtml(text string) template.HTML {
    return template.HTML(text)
}

type Template interface {
    ExecuteTemplate(wr io.Writer, name string, data interface{}) error
    Lookup(name string) *template.Template
    Templates() []*template.Template
    New(name string) *template.Template
    LoadTemplates(absPath string)
    AddTemplate(name, tpl string) error
}

type templateErr struct {
    name string
    err  error
}

type GoHtmlTemplate struct {
    template.Template
    errors []*templateErr
}

func NewTemplate() Template {
    var templates = &GoHtmlTemplate{
        Template: *template.New(""),
        errors:   make([]*templateErr, 0),
    }

    funcMap := template.FuncMap{
        "urlize":    helpers.Urlize,
        "gt":        Gt,
        "isset":     IsSet,
        "echoParam": ReturnWhenSet,
        "safeHtml":  SafeHtml,
        "first":     First,
        "highlight": Highlight,
    }

    templates.Funcs(funcMap)

    templates.LoadEmbedded()
    return templates
}

func (t *GoHtmlTemplate) LoadEmbedded() {
}

func (t *GoHtmlTemplate) AddInternalTemplate(prefix, name, tpl string) error {
    return t.AddTemplate("_internal/"+prefix+"/"+name, tpl)
}

func (t *GoHtmlTemplate) AddTemplate(name, tpl string) error {
    _, err := t.New(name).Parse(tpl)
    if err != nil {
        t.errors = append(t.errors, &templateErr{name: name, err: err})
    }
    return err
}

func (t *GoHtmlTemplate) AddTemplateFile(name, path string) error {
    b, err := ioutil.ReadFile(path)
    if err != nil {
        return err
    }
    s := string(b)
    _, err = t.New(name).Parse(s)
    if err != nil {
        t.errors = append(t.errors, &templateErr{name: name, err: err})
    }
    return err
}

func (t *GoHtmlTemplate) generateTemplateNameFrom(base, path string) string {
    return filepath.ToSlash(path[len(base)+1:])
}

func ignoreDotFile(path string) bool {
    return filepath.Base(path)[0] == '.'
}

func (t *GoHtmlTemplate) LoadTemplates(absPath string) {
    walker := func(path string, fi os.FileInfo, err error) error {
        if err != nil {
            return nil
        }

        if !fi.IsDir() {
            if ignoreDotFile(path) {
                return nil
            }

            tplName := t.generateTemplateNameFrom(absPath, path)

            if strings.HasSuffix(path, ".amber") {
                compiler := amber.New()
                // Parse the input file
                if err := compiler.ParseFile(path); err != nil {
                    return nil
                }

                // note t.New(tplName)
                if _, err := compiler.CompileWithTemplate(t.New(tplName)); err != nil {
                    return err
                }

            } else {
                t.AddTemplateFile(tplName, path)
            }
        }
        return nil
    }

    filepath.Walk(absPath, walker)
}