go-vise

page.go (9985B)

---

 package render
 
 import (
 	"bytes"
 	"context"
 	"fmt"
 	"strings"
 	"text/template"
 
 	"git.defalsify.org/vise.git/cache"
 	"git.defalsify.org/vise.git/resource"
 )
 
 // Page exectues output rendering into pages constrained by size.
 type Page struct {
 	cacheMap map[string]string // Mapped content symbols
 	cache cache.Memory // Content store.
 	resource resource.Resource // Symbol resolver.
 	menu *Menu // Menu rendererer.
 	sink *string // Content symbol rendered by dynamic size.
 	sizer *Sizer // Process size constraints.
 	err error // Error state to prepend to output.
 	extra string // Extra content to append to received template
 }
 
 // NewPage creates a new Page object.
 func NewPage(cache cache.Memory, rs resource.Resource) *Page {
 	return &Page{
 		cache: cache,
 		cacheMap: make(map[string]string),
 		resource: rs,
 	}
 }
 
 // WithMenu sets a menu renderer for the page.
 func(pg *Page) WithMenu(menu *Menu) *Page {
 	pg.menu = menu.WithResource(pg.resource)
 	//if pg.sizer != nil {
 	//	pg.sizer = pg.sizer.WithMenuSize(pg.menu.ReservedSize())
 	//}
 	return pg
 }
 
 // WithSizer sets a size constraints definition for the page.
 func(pg *Page) WithSizer(sizer *Sizer) *Page {
 	pg.sizer = sizer
 	//if pg.menu != nil {
 		//pg.sizer = pg.sizer.WithMenuSize(pg.menu.ReservedSize())
 	//}
 	return pg
 }
 
 // WithError adds an error to prepend to the page output.
 func(pg *Page) WithError(err error) *Page {
 	pg.err = err
 	return pg
 }
 
 // Error implements error interface.
 func(pg *Page) Error() string {
 	if pg.err != nil {
 		return pg.err.Error()
 	}
 	return ""
 }
 
 // Usage returns size used by values and menu, and remaining size available
 func(pg *Page) Usage() (uint32, uint32, error) {
 	var l int
 	var c uint16
 	for k, v := range pg.cacheMap {
 		l += len(v)
 		sz, err := pg.cache.ReservedSize(k)
 		if err != nil {
 			return 0, 0, err
 		}
 		c += sz
 	}
 	r := uint32(l)
 	rsv := uint32(c)-r
 	//if pg.menu != nil {
 	//	r += uint32(pg.menu.ReservedSize())
 	//}
 	return r, rsv, nil
 }
 
 // Map marks the given key for retrieval.
 //
 // After this, Val() will return the value for the key, and Size() will include the value size and limitations in its calculations.
 //
 // Only one symbol with no size limitation may be mapped at the current level.
 func(pg *Page) Map(key string) error {
 	v, err := pg.cache.Get(key)
 	if err != nil {
 		return err
 	}
 	l, err := pg.cache.ReservedSize(key)
 	if err != nil {
 		return err
 	}
 	if l == 0 {
 		if pg.sink != nil && *pg.sink != key {
 			return fmt.Errorf("sink already set to symbol '%v'", *pg.sink)
 		}
 		pg.sink = &key
 	}
 	pg.cacheMap[key] = v
 	if pg.sizer != nil {
 		err := pg.sizer.Set(key, l)
 		if err != nil {
 			return err
 		}
 	}
 	Logg.Tracef("mapped", "key", key)
 	return nil
 }
 
 // Val gets the mapped content for the given symbol.
 //
 // Fails if key is not mapped.
 func(pg *Page) Val(key string) (string, error) {
 	r := pg.cacheMap[key]
 	if len(r) == 0 {
 		return "", fmt.Errorf("key %v not mapped", key)
 	}
 	return r, nil
 }
 
 // Sizes returned the actual used bytes by each mapped symbol.
 func(pg *Page) Sizes() (map[string]uint16, error) {
 	sizes := make(map[string]uint16)
 	var haveSink bool
 	for k, _ := range pg.cacheMap {
 		l, err := pg.cache.ReservedSize(k)
 		if err != nil {
 			return nil, err
 		}
 		if l == 0 {
 			if haveSink {
 				panic(fmt.Sprintf("duplicate sink for %v", k))
 			}
 			haveSink = true
 		}
 	}
 	return sizes, nil
 }
 
 // RenderTemplate is an adapter to implement the builtin golang text template renderer as resource.RenderTemplate.
 func(pg *Page) RenderTemplate(ctx context.Context, sym string, values map[string]string, idx uint16) (string, error) {
 	tpl, err := pg.resource.GetTemplate(ctx, sym)
 	if err != nil {
 		return "", err
 	}
 	tpl += pg.extra
 	if pg.err != nil {
 		derr := pg.Error()
 		Logg.DebugCtxf(ctx, "prepending error", "err", pg.err, "display", derr)
 		if len(tpl) == 0 {
 			tpl = derr
 		} else {
 			tpl = fmt.Sprintf("%s\n%s", derr, tpl)
 		}
 	}
 	if pg.sizer != nil {
 		values, err = pg.sizer.GetAt(values, idx)
 		if err != nil {
 			return "", err
 		}
 	} else if idx > 0 {
 		return "", fmt.Errorf("sizer needed for indexed render")
 	}
 	Logg.Debugf("render for", "index", idx)
 	
 	tp, err := template.New("tester").Option("missingkey=error").Parse(tpl)
 	if err != nil {
 		return "", err
 	}
 
 	b := bytes.NewBuffer([]byte{})
 	err = tp.Execute(b, values)
 	if err != nil {
 		return "", err
 	}
 	return b.String(), err
 }
 
 // Render renders the current mapped content and menu state against the template associated with the symbol.
 func(pg *Page) Render(ctx context.Context, sym string, idx uint16) (string, error) {
 	var err error
 
 	values, err := pg.prepare(ctx, sym, pg.cacheMap, idx)
 	if err != nil {
 		return "", err
 	}
 
 	return pg.render(ctx, sym, values, idx)
 }
 
 // Reset prepared the Page object for re-use.
 //
 // It clears mappings and removes the sink definition.
 func(pg *Page) Reset() {
 	pg.sink = nil
 	pg.extra = ""
 	pg.cacheMap = make(map[string]string)
 	if pg.menu != nil {
 		pg.menu.Reset()
 	}
 	if pg.sizer != nil {
 		pg.sizer.Reset()
 	}
 }
 
 // extract sink values to separate array, and set the content of sink in values map to zero-length string.
 //
 // this allows render of page with emptry content the sink symbol to discover remaining capacity.
 func(pg *Page) split(sym string, values map[string]string) (map[string]string, string, []string, error) {
 	var sink string
 	var sinkValues []string
 	noSinkValues := make(map[string]string)
 
 	for k, v := range values {
 		sz, err := pg.cache.ReservedSize(k)
 		if err != nil {
 			return nil, "", nil, err
 		}
 		if sz == 0 {
 			sink = k
 			sinkValues = strings.Split(v, "\n")
 			v = ""
 			Logg.Infof("found sink", "sym", sym, "sink", k)
 		}
 		noSinkValues[k] = v
 	}
 	
 	if sink == "" {
 		Logg.Tracef("no sink found", "sym", sym)
 		return values, "", nil, nil
 	}
 	return noSinkValues, sink, sinkValues, nil
 }
 
 // flatten the sink values array into a paged string.
 //
 // newlines (within the same page) render are defined by NUL (0x00).
 //
 // pages are separated by LF (0x0a).
 func(pg *Page) joinSink(sinkValues []string, remaining uint32, menuSizes [4]uint32) (string, uint16, error) {
 	l := 0
 	var count uint16
 	tb := strings.Builder{}
 	rb := strings.Builder{}
 
 	// remaining is remaining less one LF
 	netRemaining := remaining - 1
 
 	// BUG: this reserves the previous browse before we know we need it
 	if len(sinkValues) > 1 {
 		netRemaining -= menuSizes[1] - 1
 	}
 
 	for i, v := range sinkValues {
 		l += len(v)
 		Logg.Tracef("processing sink", "idx", i, "value", v, "netremaining", netRemaining, "l", l)
 		if uint32(l) > netRemaining - 1 {
 			if tb.Len() == 0 {
 				return "", 0, fmt.Errorf("capacity insufficient for sink field %v", i)
 			}
 			rb.WriteString(tb.String())
 			rb.WriteRune('\n')
 			c := uint32(rb.Len())
 			pg.sizer.AddCursor(c)
 			tb.Reset()
 			l = 0
 			if count == 0 {
 				netRemaining -= menuSizes[2]
 			}
 			count += 1
 		}
 		if tb.Len() > 0 {
 			tb.WriteByte(byte(0x00))
 			l += 1
 		}
 		tb.WriteString(v)
 	}
 
 	if tb.Len() > 0 {
 		rb.WriteString(tb.String())
 		count += 1
 	}
 
 	r := rb.String()
 	r = strings.TrimRight(r, "\n")
 	return r, count, nil
 }
 
 func(pg *Page) applyMenuSink(ctx context.Context) ([]string, error) {
 	s, err := pg.menu.WithDispose().WithPages().Render(ctx, 0)
 	if err != nil {
 		return nil, err
 	}
 	values := strings.Split(s, "\n")
 	return values, nil
 }
 
 // render menu and all syms except sink, split sink into display chunks
 func(pg *Page) prepare(ctx context.Context, sym string, values map[string]string, idx uint16) (map[string]string, error) {
 	if pg.sizer == nil {
 		return values, nil
 	}
 
 	// extract sink values
 	noSinkValues, sink, sinkValues, err := pg.split(sym, values)
 	if err != nil {
 		return nil, err
 	}
 
 	// check if menu is sink aswell, fail if it is.
 	if pg.menu != nil {
 		if pg.menu.IsSink() {
 			if sink != "" {
 				return values, fmt.Errorf("cannot use menu as sink when sink already mapped")
 			}
 			sinkValues, err = pg.applyMenuSink(ctx)
 			if err != nil {
 				return nil, err
 			}
 			sink = "_menu"
 			pg.extra = "\n{{._menu}}"
 			pg.sizer.sink = sink
 			noSinkValues[sink] = ""
 			Logg.DebugCtxf(ctx, "menu is sink", "items", len(sinkValues))
 		}
 	}
 
 	// pre-render template without sink
 	// this includes the menu before any browsing options have been added
 	pg.sizer.AddCursor(0)
 	s, err := pg.render(ctx, sym, noSinkValues, 0)
 	if err != nil {
 		return nil, err
 	}
 
 	// this is the available bytes left for sink content and browse menu
 	remaining, ok := pg.sizer.Check(s)
 	if !ok {
 		return nil, fmt.Errorf("capacity exceeded")
 	}
 
 	// pre-calculate the menu sizes for all browse conditions
 	var menuSizes [4]uint32
 	if pg.menu != nil {
 		menuSizes, err = pg.menu.Sizes(ctx)
 		if err != nil {
 			return nil, err
 		}
 	}
 	Logg.Debugf("calculated pre-navigation allocation", "bytes", remaining, "menusizes", menuSizes)
 
 	// process sink values array into newline-separated string
 	sinkString, count, err := pg.joinSink(sinkValues, remaining, menuSizes)
 	if err != nil {
 		return nil, err
 	}
 	noSinkValues[sink] = sinkString
 
 	// update the page count of the menu
 	if pg.menu != nil {
 		pg.menu = pg.menu.WithPageCount(count)
 	}
 
 	// write all sink values to log.
 	for i, v := range strings.Split(sinkString, "\n") {
 		Logg.Tracef("nosinkvalue", "idx", i, "value", v)
 	}
 
 	return noSinkValues, nil
 }
 
 // render template, menu (if it exists), and audit size constraint (if it exists).
 func(pg *Page) render(ctx context.Context, sym string, values map[string]string, idx uint16) (string, error) {
 	var ok bool
 	r := ""
 	s, err := pg.RenderTemplate(ctx, sym, values, idx)
 	if err != nil {
 		return "", err
 	}
 	Logg.Debugf("rendered template", "bytes", len(s))
 	r += s
 
 	if pg.menu != nil {
 		s, err = pg.menu.Render(ctx, idx)
 		if err != nil {
 			return "", err
 		}
 		l := len(s)
 		Logg.Debugf("rendered menu", "bytes", l)
 		if l > 0 {
 			r += "\n" + s
 		}
 	}
 
 	if pg.sizer != nil {
 		_, ok = pg.sizer.Check(r)
 		if !ok {
 			return "", fmt.Errorf("limit exceeded: %v", pg.sizer)
 		}
 	}
 	return r, nil
 }