package api

import (
	"context"
	"encoding/json"
	"strings"

	"github.com/ponzischeme89/memby/server/internal/config"
	"github.com/ponzischeme89/memby/server/internal/recommend"
	"github.com/ponzischeme89/memby/server/internal/store"
)

// sectionDefinitionKeys are the three configuration values that hold a page's row
// composition. A layout override can be set on any of them, and the home payload is the
// single row source for all three browse destinations on the television, so all three are
// merged into one lookup.
var sectionDefinitionKeys = []string{
	"home.sectionDefinitions",
	"movies.sectionDefinitions",
	"tv.sectionDefinitions",
}

// rowLayoutOverrides collects every operator-pinned card shape from the section
// definitions, keyed by the definition id. An invalid or empty layout is not an override.
func rowLayoutOverrides(policy store.FeaturePolicy) map[string]string {
	overrides := map[string]string{}
	for _, key := range sectionDefinitionKeys {
		raw, ok := policy.Values[key]
		if !ok {
			continue
		}
		var definitions []config.RemoteSectionDefinition
		if json.Unmarshal(raw, &definitions) != nil {
			continue
		}
		for _, definition := range definitions {
			switch definition.Layout {
			case config.SectionLayoutPoster, config.SectionLayoutThumb:
				id := strings.TrimSpace(definition.ID)
				if id != "" {
					overrides[id] = definition.Layout
				}
			}
		}
	}
	return overrides
}

// applyRowLayoutOverrides stamps the pinned card shape onto each finished row. A row is
// matched by its exact id first, then by a section id it is a child of ("for-you" pins
// "for-you:home:evening" too) — the same rule applyRemoteHomeSections uses on the
// television to rank a family of rows together. A row that already carries a layout (none
// do today) is left alone. Pure, so it can be pinned by a test.
func applyRowLayoutOverrides(rows []recommend.Row, overrides map[string]string) []recommend.Row {
	if len(overrides) == 0 {
		return rows
	}
	for index := range rows {
		if rows[index].Layout != "" {
			continue
		}
		if layout, ok := overrides[rows[index].ID]; ok {
			rows[index].Layout = layout
			continue
		}
		for section, layout := range overrides {
			if strings.HasPrefix(rows[index].ID, section+":") {
				rows[index].Layout = layout
				break
			}
		}
	}
	return rows
}

func (s *Server) applyRowLayouts(ctx context.Context, rows []recommend.Row) []recommend.Row {
	return applyRowLayoutOverrides(rows, rowLayoutOverrides(s.currentFeaturePolicy(ctx)))
}