package tide

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"

	"github.com/goccy/go-yaml"
	"github.com/goccy/go-yaml/token"
)

func (b *Body) UnmarshalYAML(data []byte) error {
	if b == nil {
		return fmt.Errorf("tide: nil body")
	}
	var s string
	if err := yaml.Unmarshal(data, &s); err != nil {
		return err
	}
	*b = Body(s)
	return nil
}

// LoadFlow reads and validates a version-1 YAML flow from path.
func LoadFlow(path string) (Flow, error) {
	raw, err := os.ReadFile(path)
	if err != nil {
		return Flow{}, fmt.Errorf("tide: read %s: %w", path, err)
	}
	return ParseFlow(raw)
}

// ParseFlow decodes a version-1 YAML flow, rejecting unknown fields.
func ParseFlow(raw []byte) (Flow, error) {
	var flow Flow
	dec := yaml.NewDecoder(bytes.NewReader(raw), yaml.DisallowUnknownField())
	if err := dec.Decode(&flow); err != nil {
		return Flow{}, fmt.Errorf("tide: parse flow: %w", err)
	}
	if err := validateFlow(flow); err != nil {
		return Flow{}, err
	}
	return flow, nil
}

// SaveFlow writes a validated flow atomically, syncing before rename.
func SaveFlow(path string, flow Flow) error {
	if err := validateFlow(flow); err != nil {
		return err
	}
	raw, err := marshalFlow(flow)
	if err != nil {
		return err
	}
	dir := filepath.Dir(path)
	if dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0o755); err != nil {
			return fmt.Errorf("tide: create fixture dir: %w", err)
		}
	}
	tmp, err := os.CreateTemp(dir, ".tide-*.tmp")
	if err != nil {
		return fmt.Errorf("tide: create temp fixture: %w", err)
	}
	tmpName := tmp.Name()
	ok := false
	defer func() {
		if !ok {
			_ = os.Remove(tmpName)
		}
	}()
	if _, err := tmp.Write(raw); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("tide: write fixture: %w", err)
	}
	if err := tmp.Sync(); err != nil {
		_ = tmp.Close()
		return fmt.Errorf("tide: sync fixture: %w", err)
	}
	if err := tmp.Close(); err != nil {
		return fmt.Errorf("tide: close fixture: %w", err)
	}
	if err := os.Rename(tmpName, path); err != nil {
		return fmt.Errorf("tide: commit fixture: %w", err)
	}
	ok = true
	return nil
}

func marshalFlow(flow Flow) ([]byte, error) {
	var b strings.Builder
	fmt.Fprintf(&b, "version: %d\n", flow.Version)
	writeKV(&b, 0, "name", flow.Name)
	if flow.Description != "" {
		writeKV(&b, 0, "description", flow.Description)
	}
	if flow.SeedHook != "" {
		writeKV(&b, 0, "seed_hook", flow.SeedHook)
	}
	b.WriteString("steps:\n")
	for _, step := range flow.Steps {
		writeStep(&b, step)
	}
	return []byte(b.String()), nil
}

func writeStep(b *strings.Builder, step Step) {
	fmt.Fprintf(b, "  - id: %s\n", encodeScalar(step.ID))
	if step.RouteID != "" {
		writeKV(b, 4, "route_id", step.RouteID)
	}
	b.WriteString("    request:\n")
	writeRequest(b, 6, step.Request)
	b.WriteString("    response:\n")
	writeResponse(b, 6, step.Response)
	writeCapture(b, 4, step.Capture)
	writeNormalize(b, 4, step.Normalize)
	writeHeaders(b, 4, step.Headers)
}

func writeRequest(b *strings.Builder, indent int, req Request) {
	writeKV(b, indent, "method", req.Method)
	writeKV(b, indent, "path", req.Path)
	if req.Query != "" {
		writeKV(b, indent, "query", req.Query)
	}
	writeHeaders(b, indent, req.Headers)
	writeBody(b, indent, string(req.Body))
}

func writeResponse(b *strings.Builder, indent int, resp Response) {
	if resp.Status != 0 {
		fmt.Fprintf(b, "%sstatus: %d\n", strings.Repeat(" ", indent), resp.Status)
	}
	writeHeaders(b, indent, resp.Headers)
	writeBody(b, indent, string(resp.Body))
	if resp.BodyFile != "" {
		writeKV(b, indent, "body_file", resp.BodyFile)
	}
	if resp.SHA256 != "" {
		writeKV(b, indent, "sha256", resp.SHA256)
	}
}

func writeCapture(b *strings.Builder, indent int, rules []CaptureRule) {
	if len(rules) == 0 {
		return
	}
	pad := strings.Repeat(" ", indent)
	fmt.Fprintf(b, "%scapture:\n", pad)
	inner := strings.Repeat(" ", indent+2)
	for _, rule := range rules {
		fmt.Fprintf(b, "%s- path: %s\n", inner, encodeScalar(rule.Path))
		fmt.Fprintf(b, "%s  as: %s\n", inner, encodeScalar(rule.As))
	}
}

func writeNormalize(b *strings.Builder, indent int, rules []NormalizeRule) {
	if len(rules) == 0 {
		return
	}
	pad := strings.Repeat(" ", indent)
	fmt.Fprintf(b, "%snormalize:\n", pad)
	inner := strings.Repeat(" ", indent+2)
	for _, rule := range rules {
		fmt.Fprintf(b, "%s- path: %s\n", inner, encodeScalar(rule.Path))
		if rule.Disable {
			fmt.Fprintf(b, "%s  disable: true\n", inner)
		}
	}
}

func writeHeaders(b *strings.Builder, indent int, headers map[string]string) {
	if len(headers) == 0 {
		return
	}
	pad := strings.Repeat(" ", indent)
	fmt.Fprintf(b, "%sheaders:\n", pad)
	keys := make([]string, 0, len(headers))
	for k := range headers {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	inner := strings.Repeat(" ", indent+2)
	for _, k := range keys {
		fmt.Fprintf(b, "%s%s: %s\n", inner, k, encodeScalar(headers[k]))
	}
}

func writeBody(b *strings.Builder, indent int, body string) {
	if body == "" {
		return
	}
	pad := strings.Repeat(" ", indent)
	header := token.LiteralBlockHeader(body)
	if header == "" {
		header = "|-"
	}
	fmt.Fprintf(b, "%sbody: %s\n", pad, header)
	inner := strings.Repeat(" ", indent+2)
	content := body
	if strings.HasSuffix(content, "\n") {
		content = content[:len(content)-1]
	}
	for _, line := range strings.Split(content, "\n") {
		b.WriteString(inner)
		b.WriteString(line)
		b.WriteByte('\n')
	}
}

func writeKV(b *strings.Builder, indent int, key, value string) {
	pad := strings.Repeat(" ", indent)
	fmt.Fprintf(b, "%s%s: %s\n", pad, key, encodeScalar(value))
}

func encodeScalar(v string) string {
	if v == "" {
		return `""`
	}
	if token.IsNeedQuoted(v) || strings.ContainsAny(v, " \t") {
		return strconv.Quote(v)
	}
	return v
}