package processing

import (
	"encoding/json"
	"fmt"
	"strconv"
	"strings"
)

// AppendFormulaConstraints appends language-agnostic title/description formula
// guidance to the enhance user template (before {{var}} render). Empty templates
// are no-ops. Shared skeleton stays in company/built-in prompts; formulas only
// constrain structure for the active language via {{language}} elsewhere.
func AppendFormulaConstraints(userTpl string, titleTemplate, descriptionTemplate any) string {
	userTpl = strings.TrimSpace(userTpl)
	titleBlock := FormatTitleFormulaConstraint(titleTemplate)
	descBlock := FormatDescriptionFormulaConstraint(descriptionTemplate)
	if titleBlock == "" && descBlock == "" {
		return userTpl
	}
	var b strings.Builder
	if userTpl != "" {
		b.WriteString(userTpl)
		b.WriteString("\n\n")
	}
	if titleBlock != "" {
		b.WriteString(titleBlock)
		if descBlock != "" {
			b.WriteString("\n\n")
		}
	}
	if descBlock != "" {
		b.WriteString(descBlock)
	}
	return b.String()
}

// FormatTitleFormulaConstraint turns categories.title_template into enhance-prompt
// constraints (element order: literal text + attribute variable keys).
func FormatTitleFormulaConstraint(template any) string {
	elements, separator, ok := parseTitleFormula(template)
	if !ok || len(elements) == 0 {
		return ""
	}
	sep := separator
	if sep == "" {
		sep = " "
	}
	var b strings.Builder
	b.WriteString("Title formula (order matters; join with ")
	b.WriteString(strconv.Quote(sep))
	b.WriteString("). Build name from Attrs using this structure:\n")
	for i, el := range elements {
		switch el.Type {
		case "text":
			fmt.Fprintf(&b, "%d. text %s\n", i+1, strconv.Quote(el.Value))
		case "variable":
			key := strings.TrimSpace(el.Value)
			if key == "" {
				continue
			}
			fmt.Fprintf(&b, "%d. attr [%s]\n", i+1, key)
		default:
			continue
		}
	}
	b.WriteString("Prefer Attrs values for [attr] slots; keep literal text as written; write name in {{language}}.")
	return strings.TrimSpace(b.String())
}

// FormatDescriptionFormulaConstraint turns categories.description_template sections
// into bullet instructions for the enhance user prompt.
func FormatDescriptionFormulaConstraint(template any) string {
	sections, ok := parseDescriptionFormulaSections(template)
	if !ok || len(sections) == 0 {
		return ""
	}
	var b strings.Builder
	b.WriteString("Description formula (REQUIRED — overrides any shorter \"1-2 sentences\" rule):\n")
	b.WriteString("Emit description as ONE HTML string covering each section in order in {{language}}.\n")
	b.WriteString("Use tags matching section type: h1/h2/h3/h4 → <hN>…</hN>, p → <p>…</p>, ul → <ul><li>…</li></ul>.\n")
	for _, s := range sections {
		typ := strings.TrimSpace(s.Type)
		instr := strings.TrimSpace(s.Instructions)
		if typ == "" && instr == "" {
			continue
		}
		if typ == "" {
			typ = "section"
		}
		if instr == "" {
			fmt.Fprintf(&b, "- %s\n", typ)
			continue
		}
		fmt.Fprintf(&b, "- %s: %s\n", typ, instr)
	}
	return strings.TrimSpace(b.String())
}

// descriptionFormulaSystemOverride is appended to the enhance system template when a
// category description_template is present so company/built-in "1-2 sentences" rules
// cannot override the per-category formula (A1 category definition pages).
const descriptionFormulaSystemOverride = `When the user message includes a "Description formula", obey those sections over any shorter "1-2 sentences" / "1-3 paragraphs" guidance: emit one HTML string using tags matching each section type (h1/h2/h3/h4, p, ul), in order, in {{language}}. Never ignore the Description formula.`

// AppendDescriptionFormulaSystemOverride strengthens the system prompt when a
// description formula is active. No-op when template is empty/unparseable.
func AppendDescriptionFormulaSystemOverride(systemTpl string, descriptionTemplate any) string {
	if FormatDescriptionFormulaConstraint(descriptionTemplate) == "" {
		return strings.TrimSpace(systemTpl)
	}
	systemTpl = strings.TrimSpace(systemTpl)
	if systemTpl == "" {
		return descriptionFormulaSystemOverride
	}
	if strings.Contains(systemTpl, "Description formula") {
		return systemTpl
	}
	return systemTpl + "\n" + descriptionFormulaSystemOverride
}

type titleFormulaElement struct {
	Type  string `json:"type"`
	Value string `json:"value"`
}

type descriptionFormulaSection struct {
	Type         string `json:"type"`
	Instructions string `json:"instructions"`
}

func parseTitleFormula(template any) (elements []titleFormulaElement, separator string, ok bool) {
	if template == nil {
		return nil, "", false
	}
	obj, err := asObjectMap(template)
	if err != nil || obj == nil {
		return nil, "", false
	}
	sep, _ := obj["separator"].(string)
	rawEls, exists := obj["elements"]
	if !exists || rawEls == nil {
		return nil, "", false
	}
	b, err := json.Marshal(rawEls)
	if err != nil {
		return nil, "", false
	}
	var parsed []titleFormulaElement
	if err := json.Unmarshal(b, &parsed); err != nil {
		return nil, "", false
	}
	out := make([]titleFormulaElement, 0, len(parsed))
	for _, el := range parsed {
		t := strings.ToLower(strings.TrimSpace(el.Type))
		v := strings.TrimSpace(el.Value)
		if t != "text" && t != "variable" {
			continue
		}
		if v == "" {
			continue
		}
		out = append(out, titleFormulaElement{Type: t, Value: v})
	}
	if len(out) == 0 {
		return nil, "", false
	}
	return out, sep, true
}

func parseDescriptionFormulaSections(template any) ([]descriptionFormulaSection, bool) {
	if template == nil {
		return nil, false
	}
	obj, err := asObjectMap(template)
	if err != nil || obj == nil {
		return nil, false
	}
	raw, exists := obj["sections"]
	if !exists || raw == nil {
		return nil, false
	}
	b, err := json.Marshal(raw)
	if err != nil {
		return nil, false
	}
	var parsed []descriptionFormulaSection
	if err := json.Unmarshal(b, &parsed); err != nil {
		return nil, false
	}
	out := make([]descriptionFormulaSection, 0, len(parsed))
	for _, s := range parsed {
		t := strings.ToLower(strings.TrimSpace(s.Type))
		instr := strings.TrimSpace(s.Instructions)
		if t == "" && instr == "" {
			continue
		}
		out = append(out, descriptionFormulaSection{Type: t, Instructions: instr})
	}
	return out, len(out) > 0
}

// categoryFormulasFor resolves title/description templates for a category key
// (unique_id or name). Explicit ProductInput fields win over the job cache map.
func categoryFormulasFor(in ProductInput, category string) (title, description any) {
	if in.TitleTemplate != nil || in.DescriptionTemplate != nil {
		return in.TitleTemplate, in.DescriptionTemplate
	}
	key := strings.ToLower(strings.TrimSpace(category))
	if key == "" || len(in.CategoryFormulasByKey) == 0 {
		return nil, nil
	}
	f, ok := in.CategoryFormulasByKey[key]
	if !ok {
		return nil, nil
	}
	return f.TitleTemplate, f.DescriptionTemplate
}

func asObjectMap(v any) (map[string]any, error) {
	switch t := v.(type) {
	case map[string]any:
		return t, nil
	case nil:
		return nil, nil
	default:
		b, err := json.Marshal(t)
		if err != nil {
			return nil, err
		}
		if len(b) == 0 || string(b) == "null" {
			return nil, nil
		}
		var obj map[string]any
		if err := json.Unmarshal(b, &obj); err != nil {
			return nil, err
		}
		return obj, nil
	}
}