// Package quill is the "Scribe" of the Coven — the interactive wizard that
// interviews a developer and emits a new spell (DETAILS, DEPENDS, BUILD,
// CONFIGURE) into the Grimoire.
//
// Replacing the original Bash Quill, this Go version uses text/template
// for type-safe file generation and an HTTP-friendly SpellData struct so
// the WebUI can drive the same interview through a modal form.
package quill

import (
        "crypto/sha512"
        "encoding/hex"
        "fmt"
        "io"
        "net/http"
        "os"
        "path/filepath"
        "text/template"
        "time"
)

// SpellData is everything the interview collects.
type SpellData struct {
        Name         string
        Version      string
        SourceURL    string
        Hash         string
        Website      string
        License      string
        Description  string
        LongDesc     string
        Dependencies []string
        Date         string
}

// GenerateSpell writes a new spell directory under `targetDir` containing
// DETAILS, DEPENDS, BUILD and CONFIGURE. Atomic "buffer-then-commit": no
// file is written until the template parses successfully.
func GenerateSpell(data SpellData, targetDir string) error {
        if data.Date == "" {
                data.Date = time.Now().Format("20060102")
        }
        if data.Hash == "" {
                // "Smart Quill" — auto-hash the upstream source.
                h, err := autoHash(data.SourceURL)
                if err == nil {
                        data.Hash = h
                }
        }

        tmpl, err := template.New("details").Parse(detailsTmpl)
        if err != nil {
                return fmt.Errorf("quill: template parse: %w", err)
        }
        if err := os.MkdirAll(targetDir, 0755); err != nil {
                return err
        }
        f, err := os.Create(filepath.Join(targetDir, "DETAILS"))
        if err != nil {
                return err
        }
        defer f.Close()
        if err := tmpl.Execute(f, data); err != nil {
                return fmt.Errorf("quill: template exec: %w", err)
        }

        // DEPENDS
        depTmpl, err := template.New("depends").Parse(dependsTmpl)
        if err != nil {
                return fmt.Errorf("quill: parse depends template: %w", err)
        }
        df, err := os.Create(filepath.Join(targetDir, "DEPENDS"))
        if err != nil {
                return fmt.Errorf("quill: create DEPENDS: %w", err)
        }
        defer df.Close()
        if err := depTmpl.Execute(df, data); err != nil {
                return fmt.Errorf("quill: exec depends template: %w", err)
        }

        // BUILD
        bf, err := os.Create(filepath.Join(targetDir, "BUILD"))
        if err != nil {
                return fmt.Errorf("quill: create BUILD: %w", err)
        }
        defer bf.Close()
        if _, err := bf.WriteString(buildTmpl); err != nil {
                return fmt.Errorf("quill: write BUILD: %w", err)
        }

        // CONFIGURE
        cf, err := os.Create(filepath.Join(targetDir, "CONFIGURE"))
        if err != nil {
                return fmt.Errorf("quill: create CONFIGURE: %w", err)
        }
        defer cf.Close()
        if _, err := cf.WriteString(configureTmpl); err != nil {
                return fmt.Errorf("quill: write CONFIGURE: %w", err)
        }

        return nil
}

// autoHash downloads the source URL and computes its SHA-512 — Quill's
// "Smart" mode that saves the developer from running sha512sum by hand.
func autoHash(url string) (string, error) {
        if url == "" {
                return "", fmt.Errorf("quill: no source URL")
        }
        client := &http.Client{Timeout: 30 * time.Second}
        resp, err := client.Get(url)
        if err != nil {
                return "", err
        }
        defer resp.Body.Close()
        if resp.StatusCode != http.StatusOK {
                return "", fmt.Errorf("quill: HTTP %d fetching %s", resp.StatusCode, url)
        }
        h := sha512.New()
        if _, err := io.Copy(h, resp.Body); err != nil {
                return "", err
        }
        return hex.EncodeToString(h.Sum(nil)), nil
}

const detailsTmpl = `SPELL={{.Name}}
VERSION={{.Version}}
SOURCE=${SPELL}-${VERSION}.tar.gz
SOURCE_URL[0]={{.SourceURL}}
SOURCE_HASH=sha512:{{.Hash}}
SOURCE_DIRECTORY="${BUILD_DIRECTORY}/${SPELL}-${VERSION}"
WEB_SITE={{.Website}}
ENTERED={{.Date}}
LICENSE[0]={{.License}}
SHORT="{{.Description}}"
cat << EOF
{{.LongDesc}}
EOF
`

const dependsTmpl = `{{range .Dependencies}}depends {{.}} ""
{{end}}`

const buildTmpl = `#!/bin/bash
# Standard BUILD script — edit as needed.
cd "$SOURCE_DIRECTORY" &&
./configure --prefix=/usr "$@" &&
make &&
make install
`

const configureTmpl = `#!/bin/bash
# CONFIGURE — interactive queries go here. The Go ICE engine reads these.
# config_query WGET_SSL "Enable SSL support?" y
`