package api

import (
	"context"
	"net/http"
	"strconv"

	"git.golem15.com/golem15/sm-seo-plugin/classes"
	"git.golem15.com/golem15/sm-seo-plugin/models"
	"gorm.io/gorm"
)

// ListRedirectsInput is the query of GET /_seo/api/v1/redirects.
type ListRedirectsInput struct {
	Page    int    `json:"page,omitempty" query:"page" jsonschema:"the page number, from 1"`
	PerPage int    `json:"per_page,omitempty" query:"per_page" jsonschema:"rows per page, at most 200 (50 by default)"`
	Search  string `json:"search,omitempty" query:"search" jsonschema:"text the source or target contains"`
	Status  int    `json:"status,omitempty" query:"status" jsonschema:"301, 302 or 410"`
	Origin  string `json:"origin,omitempty" query:"origin" jsonschema:"manual, slug, import, mcp or notfound"`
}

// RedirectIDInput names one redirect.
type RedirectIDInput struct {
	ID uint `json:"id" path:"id" jsonschema:"the redirect id"`
}

// CreateRedirectInput is the body of POST /_seo/api/v1/redirects.
type CreateRedirectInput struct {
	Source        string  `json:"source" jsonschema:"the address to redirect: a path (exact), a pattern where * matches any text, or a regular expression"`
	Target        *string `json:"target,omitempty" jsonschema:"where to send visitors: a path or an absolute URL; empty for 410"`
	Status        *int    `json:"status,omitempty" jsonschema:"301 (the default), 302 or 410"`
	Match         *string `json:"match,omitempty" jsonschema:"exact (the default), pattern or regex"`
	Query         *string `json:"query,omitempty" jsonschema:"ignore (the default) or pass the request's query string to the target"`
	IgnoreCase    *bool   `json:"ignore_case,omitempty" jsonschema:"match the source without letter case"`
	TrailingSlash *bool   `json:"trailing_slash,omitempty" jsonschema:"match the source with and without a trailing slash (default true)"`
	Note          *string `json:"note,omitempty" jsonschema:"an internal note"`
}

// UpdateRedirectInput is PUT /_seo/api/v1/redirects/{id}: only the fields
// sent are changed.
type UpdateRedirectInput struct {
	ID            uint    `json:"id" path:"id" jsonschema:"the redirect id"`
	Source        *string `json:"source,omitempty" jsonschema:"the address to redirect"`
	Target        *string `json:"target,omitempty" jsonschema:"where to send visitors; empty for 410"`
	Status        *int    `json:"status,omitempty" jsonschema:"301, 302 or 410"`
	Match         *string `json:"match,omitempty" jsonschema:"exact, pattern or regex"`
	Query         *string `json:"query,omitempty" jsonschema:"ignore or pass"`
	IgnoreCase    *bool   `json:"ignore_case,omitempty" jsonschema:"match without letter case"`
	TrailingSlash *bool   `json:"trailing_slash,omitempty" jsonschema:"match with and without a trailing slash"`
	Note          *string `json:"note,omitempty" jsonschema:"an internal note"`
}

// RedirectJSON is a redirect in an answer.
func RedirectJSON(r models.Redirect) map[string]any {
	out := classes.RedirectValues(r)
	out["status"] = int(r.Status)
	out["id"] = r.ID
	out["created_at"] = r.CreatedAt
	out["updated_at"] = r.UpdatedAt
	return out
}

// redirectAnswer is a write's answer: the redirect and, for a chain, the
// chain warning (D-19: a chain is saved, a loop refused).
func redirectAnswer(ctx context.Context, svc *classes.Service, r models.Redirect, check classes.RedirectCheck) map[string]any {
	out := map[string]any{"data": RedirectJSON(r)}
	if check.Chain {
		notice := classes.ChainNotice(check)[0]
		out["warnings"] = []map[string]any{{
			"kind":    "redirect_chain",
			"path":    check.Path,
			"final":   check.Final,
			"message": svc.PhraseCtx(ctx, notice.Message, notice.Params),
		}}
	}
	return out
}

// ListRedirects serves GET /_seo/api/v1/redirects: newest change first,
// filtered by search text, status and origin.
func ListRedirects(service func() *classes.Service) http.HandlerFunc {
	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
		db, err := read(ctx, svc)
		if err != nil {
			return 0, nil, err
		}
		in := listParams(r)
		q := db.Model(&models.Redirect{}).Order("updated_at DESC NULLS LAST, id DESC")
		if in.Search != "" {
			p := like(in.Search)
			q = q.Where("lower(source) LIKE ? OR lower(target) LIKE ?", p, p)
		}
		if s, err := strconv.Atoi(r.URL.Query().Get("status")); err == nil && s > 0 {
			q = q.Where("status = ?", s)
		}
		if o := r.URL.Query().Get("origin"); o != "" {
			q = q.Where("origin = ?", o)
		}
		var rows []models.Redirect
		total, err := paginate(q, in, &rows)
		if err != nil {
			return 0, nil, err
		}
		out := make([]map[string]any, 0, len(rows))
		for _, row := range rows {
			out = append(out, RedirectJSON(row))
		}
		return http.StatusOK, listBody(out, in, total), nil
	})
}

// ShowRedirect serves GET /_seo/api/v1/redirects/{id}.
func ShowRedirect(service func() *classes.Service) http.HandlerFunc {
	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
		id, err := pathID(r, "id")
		if err != nil {
			return 0, nil, err
		}
		db, err := read(ctx, svc)
		if err != nil {
			return 0, nil, err
		}
		row, err := classes.LoadRedirect(db, id)
		if err != nil {
			return 0, nil, err
		}
		return http.StatusOK, map[string]any{"data": RedirectJSON(row)}, nil
	})
}

// CreateRedirect serves POST /_seo/api/v1/redirects: 201 with the
// redirect (and a chain warning), 422 redirect_loop for a loop (D-19) or
// validation_failed for invalid fields. The origin is mcp through MCP.
func CreateRedirect(service func() *classes.Service) http.HandlerFunc {
	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
		var body classes.RedirectFields
		if err := decode(r, maxBody, &body); err != nil {
			return 0, nil, err
		}
		if problems := body.Problems(); len(problems) > 0 {
			return 0, nil, &classes.ProblemsError{Problems: problems}
		}
		row := models.NewRedirect()
		row.Origin = classes.RedirectOrigin(ctx)
		body.Apply(&row)
		var check classes.RedirectCheck
		err := write(ctx, svc, func(ctx context.Context, tx *gorm.DB) error {
			var err error
			check, err = svc.SaveRedirect(ctx, tx, &row)
			return err
		})
		if err != nil {
			return 0, nil, err
		}
		return http.StatusCreated, redirectAnswer(ctx, svc, row, check), nil
	})
}

// UpdateRedirect serves PUT /_seo/api/v1/redirects/{id}: the fields sent
// change; a loop is refused like a create.
func UpdateRedirect(service func() *classes.Service) http.HandlerFunc {
	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
		id, err := pathID(r, "id")
		if err != nil {
			return 0, nil, err
		}
		var body classes.RedirectFields
		if err := decode(r, maxBody, &body); err != nil {
			return 0, nil, err
		}
		if problems := body.Problems(); len(problems) > 0 {
			return 0, nil, &classes.ProblemsError{Problems: problems}
		}
		var row models.Redirect
		var check classes.RedirectCheck
		err = write(ctx, svc, func(ctx context.Context, tx *gorm.DB) error {
			var err error
			if row, err = classes.LoadRedirect(tx, id); err != nil {
				return err
			}
			body.Apply(&row)
			check, err = svc.SaveRedirect(ctx, tx, &row)
			return err
		})
		if err != nil {
			return 0, nil, err
		}
		return http.StatusOK, redirectAnswer(ctx, svc, row, check), nil
	})
}

// DeleteRedirect serves DELETE /_seo/api/v1/redirects/{id}.
func DeleteRedirect(service func() *classes.Service) http.HandlerFunc {
	return manage(service, func(ctx context.Context, svc *classes.Service, r *http.Request) (int, any, error) {
		id, err := pathID(r, "id")
		if err != nil {
			return 0, nil, err
		}
		err = write(ctx, svc, func(ctx context.Context, tx *gorm.DB) error {
			row, err := classes.LoadRedirect(tx, id)
			if err != nil {
				return err
			}
			return svc.DeleteRedirect(ctx, tx, row)
		})
		if err != nil {
			return 0, nil, err
		}
		return http.StatusOK, map[string]any{"deleted": id}, nil
	})
}